Allan McNish: Former champions Jenson Button & Kimi Raikkonen could exit F1

Are we witnessing the final races of two long-serving former world champions?

And which drivers might Ferrari, McLaren and Williams target as they attempt to bridge the gap to the all-conquering Mercedes?

Ferrari - Raikkonen should be dropped

"Do you know something I don't?" Raikkonen, right, could be out of F1 at the end of this season

Sebastian Vettel is definitely staying for 2017, but the team have to decide whether to keep the 2007 world champion Kimi Raikkonen, whose contract ends this year.

This is a prime seat. It's not a Mercedes, but it is the next best thing at the moment. And Ferrari have their own special pull.

In my opinion, Ferrari should look at a change. In fact, I think they should have done so last year. I can see why they didn't given the new management and technical structure was still bedding in, but things have settled down now and they have to build towards the future.

Whether you like it or not, Raikkonen, who turns 37 in October, is not the future. He is a former world champion, but his best performances are in the past.

The last driver to win the world title with Ferrari, the Finn's form has been questionable since he rejoined the team in 2014. He was comprehensively out-paced by Fernando Alonso that year - and by Vettel when the four-time world champion arrived in 2015.

Raikkonen has improved this season, but has he done enough? I keep looking to the Spanish Grand Prix, where he was second behind Red Bull's Max Verstappen. He never applied enough pressure when he had the chance to chase the Dutchman down, not once showing his nose to Verstappen.

In reality, the question is not whether Raikkonen is good enough to keep his place at Ferrari - it's whether there is someone better.

Lots of drivers have been linked with them over the last few years. Among them was Nico Hulkenberg, who was on Ferrari's list when they re-signed Raikkonen for 2014. In fact, I understand 28-year-old Hulkenberg got as close as signing a Ferrari contract - it just wasn't signed by Ferrari.

But the German has been outshone by Force India team-mate Sergio Perez this year, especially in the last few races. Mexican Perez, 26, was a Ferrari young driver not so long ago and has the backing of billionaire Carlos Slim Jr, who is on the board of tobacco giant Philip Morris, the team's biggest sponsor.

Williams driver Valtteri Bottas has also been linked to Ferrari, but, as with Hulkenberg, is not a compelling candidate right now. Then there is Romain Grosjean, who moved to the new Ferrari-backed Haas team this season with the hope of getting on to the Italian team's radar.

Without doubt, Red Bull's Daniel Ricciardo would be the strongest option. If I was at Ferrari, I would have approached him after Monaco, where strategy errors cost him victory for the second race in succession. But it would be hard to get him given he is under contract.

Beyond that, the only other potentially available driver who I think would do a good job would be Toro Rosso's Carlos Sainz. He is quick, strong and consistent. The 21-year-old also speaks Italian, so would fit in nicely. Although Red Bull say they have taken up their contractual option on him and plan for him to stay at Toro Rosso next season, there is not an obvious progression for Sainz within Red Bull, as they will be sticking with Ricciardo and Verstappen as their senior drivers next year. So Ferrari would be an appealing option.

In my view, Ferrari's choice seems to come down to Sainz or Perez. I think both of them would be a better option than Raikkonen. Longer-term, Ferrari have some potentially very good drivers in their academy in Antonio Fuoco and Charles Leclerc. They should also look at GP2 front-runner Antonio Giovinazzi, who had a double win in Baku.

McLaren - Vandoorne not Button

Is this awkward for you, Fernando? Vandoorne, left, has already beaten Button this season

The choice at McLaren is much more straightforward. Alonso, 34, is under contract until the end of 2017 and his team-mate will be either Button or reserve driver Stoffel Vandoorne.

Button, champion in 2009, clearly wants to stay in F1, but the decision is not his. In my view, it is a slam-dunk in favour of Vandoorne.

McLaren say they are waiting until September to make the decision, which is when new chief executive officer Jost Capito is expected to finally join from VW. In reality, though, I suspect the decision is as good as made already.

Vandoorne has youth on his side and performed exceptionally well when he made his grand prix debut in Bahrain earlier this year, standing in for Alonso, who was ruled out by injury. The Belgian flew in from Japan on the Friday morning but out-qualified Button and went on to score a point in the race.

McLaren have an ageing driver line-up right now. Alonso and 36-year-old Button have three world titles between them, but those were all won several years ago and they cannot trade on them now.

Both need to perform - and they are undoubtedly doing that, especially Alonso. But Button continues to pull out good performances and results, too. However, Vandoorne is too good a prospect to let slip through their fingers and is the right choice.

The kids were alright: Button and Alonso made their F1 debuts in the early noughties

Williams - A lifeline for Button?

Williams are interested in signing Button for 2017 to partner Bottas. The Englishman would replace Felipe Massa and would be a good, solid choice. But whether it is such an appealing prospect for Button is a different question.

As the Renault power-unit has improved this season, Williams have increasingly slipped behind Red Bull. If Honda can sort itself out for 2017, then there is the real possibility of Williams being behind McLaren as well.

That would mean Button could go from qualifying about 12th for McLaren this year to qualifying about 12th for Williams next year. That's not an especially enticing thought after the frustrations of the last two years, but Button loves racing so much that I suspect he would take it if it was on offer.

Button is not the only choice for Williams should they replace Massa. They need someone with experience, but they have that in Bottas, so they could look to youth. Equally, Williams may have to take finance into the equation, too.

They have to balance the books, and they don't have the backing of the big teams. Button would not earn anything like his current $15m salary if he went to Williams - and they may prefer to take a driver who costs less or even perhaps brings a measure of sponsorship to the team.

Been there, mate: Button made his debut for Williams back in 2000

Renault - Palmer on rocky ground

There is another more potentially enticing team - and that is Renault. They are struggling this year, still suffering from the lack of investment put into this year's car by the previous owners when they were Lotus.

But long-term, as a manufacturer with a commitment to F1 until 2024, they are an appealing prospect. You could see someone trying to lock themselves in there with a three-year contract.

Both of this year's drivers, Denmark's Kevin Magnussen, 23, and Briton Jolyon Palmer, 25, are hoping to be retained. But, at the moment, Palmer's seat is under the most scrutiny. Sainz is an option here, too, as is reserve driver Esteban Ocon.

Mercedes - Rosberg set to stay

Only a madman would leave Mercedes. Or one who had had enough of Lewis Hamilton winning titles instead of him...

Finally, the world champions. Nico Rosberg is out of contract at the end of the season but there is next to no chance that he will leave. The team want to keep him and he wants to stay.

Negotiations are ongoing, but there is no real doubt that they will come to an agreement. For a start, Rosberg, 31, does not have any other options that are anywhere near as good. And do you really think Mercedes would let go a driver who has won five races already this season and is leading - and could very well win - the world championship?

If Rosberg wins the title, it is inconceivable Mercedes would want him to go anywhere else. He is a German in a German team, and silky smooth when it comes to being a brand ambassador for Mercedes-Benz, an important aspect for the paymasters.

Three-time champion Lewis Hamilton is not going anywhere either, so retaining the status quo is the ideal scenario from an on-track and off-track point of view. And as much as Hamilton and Rosberg have had their fiery moments with each other, their rivalry has been containable.

Allan McNish was talking to BBC Sport's Andrew Benson

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