As the final pieces of the F1 grid for 2016 begin to fall into place, with the confirmations of Kimi Raikkonen and Nico Hulkenberg, all eyes are now on the McLaren pair Jenson Button and Kevin Magnussen.

Magnussen, who raced for McLaren in 2014, was demoted to reserve driver for this season with the arrival of Fernando Alonso in an 11th hour decision before the start of the season, that split the shareholders and management of the team.

For 2016, McLaren has three options: retain Button, restore Magnussen or promote their other young protege Stoffel Vandoorne, who is dominating the GP2 series, much as their former protege Lewis Hamilton did in 2006.

Button is by far the most expensive option and with no clear prospect of a title sponsor for the team and with McLaren Honda’s disappointing performance in 2015 likely to lead to a significant drop in prize money income, there is speculation that Button would have to accept a cut in salary to continue.

He will have to take a view on that and whether he believes that Honda will be able to make meaningful progress in 2016 or whether he would be making up the numbers again.

Button had been linked to a move to Williams if Valtteri Bottas replaced Kimi Raikkonen at Ferrari, but with the 2007 world champions staying put, it seems unlikely that Bottas will leave Williams after all.

Vandoorne currently leads the GP2 standings by 105 points and has taken five wins; all of them feature races, so far this season. The Belgian driver clearly needs an opportunity to race in F1 and if it doesn't come at McLaren it needs to come from somewhere else. But he has time on his side and could wait to see what happens with Button. If it's anything like last time, the decision from McLaren will come very late. They can afford to play that game.

Magnussen cannot. After a year on the sidelines, the Dane needs to race in 2016 and as the doors are now closing, he needs to do a deal in the next few weeks.

Magnussen recently said there would be “no way in hell” he would not be racing in 2016 – although he admitted that could be in another category if no opportunities open up in F1.

His best chance looks to be the new Haas F1 team, which is starting in F1 next season. The word in F1 is that they have already agreed with their technical partner Ferrari to take reserve driver Esteban Gutierrez for one of the seats. But they would like another experienced driver for the other seat or an American if one fits the bill. Alex Rossi is doing well in GP2 this season and is eligible for a super licence, while Magnussen has podium winning pedigree and the record of having out qualified Button across the 2014 season by around 0.15s on average.

He was described by one team boss in the Spa paddock as a 'sleeper' in the driver market.

Now that Haas' prime target Nico Hulkenberg has committed to Force India for another two seasons. Magnussen is close to the front of the queue for the drive and would be an ideal candidate as he is not only a fast benchmark for the developing team, but also speaks a high standard of English in a way that Americans and their sponsors would understand, which is important. He scored a podium on debut and generally performed well in a difficult McLaren chassis last year.

Magnussen said last week, “There will not be one more year without racing - no way in hell. I'll stay for one year like this and then hopefully something will happen [in F1], and if not you'll have to move on and do something else.

"If I don't get a [race] drive then I might do something else and if I can be reserve driver as well then that'll be good. But I hope that's not going to be it - I hope to be back in Formula 1 next year."

McLaren were recently forced to deny rumours that Vandoorne had already been signed to partner Alonso in 2016, but it seems unlikely he won’t be on the F1 grid one way or another next year.

Renault’s uncertain F1 future is another interesting twist in the F1 driver market. If the French manufacturer does go ahead and buy the Enstone-based Lotus team and return to manufacturer status, it could put Pastor Maldonado’s place with the team in jeopardy.

Sauber has already tied up its two drivers Marcus Ericsson and Felipe Nasr, so the doors are closing fast for drivers wanting to get a place on the F1 grid for 2016.