Lewis Hamilton will have a new team mate in Mercedes Formula 1 team, in 2017. Nico Rosberg, the reigning champion, surprised virtually everyone by announcing today his retirement from competition. So much for those who were writing that Hamilton might be sacked; would Mercedes lose both their drivers? Rosberg has earned his place in the Hall of Champions. Now let's look at the future: Hamilton is chasing his fourth title and will have a new rival to compare directly with.

Likely candidates to Mercedes opening

The main candidate is Pascal Wehrlein.

He is a Mercedes "protegé" and did quite well at Manor on his first F1 season, scoring the team's sole point with a brilliant performance in Austria.

He was being targeted as a future Mercedes main driver, so it seems the opening appeared earlier than expected.

Esteban Ocon is also a Mercedes favourite, and some in the F1 paddock were surprised that Force India chose him instead of Pascal Wehrlein. The midfield team also runs Mercedes engines (like Manor). It's unclear if Ocon's contract has some clause allowing him to leave to Mercedes; if not, that would clearly open way for Wehrlein, who does not yet have a contract for 2017.

Some social media opinions are pointing at Fernando Alonso. Of course, the best driver of the grid - still reckoned as so by many - jumping into the best car.

But there are tons of questions. Would McLaren-Honda let him go? Would Mercedes pay for his release from McLaren? Why would Mercedes do that, having Hamilton and two solid "young guns" at disposal? And why would Mercedes pay to bring someone who did not get along well with Hamilton, when both were at McLaren?

Past champions early retired

We had just mentioned the longevity records in Formula One, remembering Michael Schumacher's appetite for Grand Prix racing (he did it in a 21-year span) and the possibility of Max Verstappen beat that record, due to his early career start. Well, for sure these questions don't apply to Nico Rosberg.

At 31 years-old, he still could do a lot in F1, even after 11 full F1 season.

The last driver to retire immediately after being champion was Alain Prost in 1993 - but the Frenchman had win his 4th title, and already 38 years.

In 2001, Mika Hakkinen retired as a 33-year-old, 11 years before his big rival Schumacher did it so. It was somewhat surprising, but the Finn showed some signs of being not motivated during that season - a difficult one, plagued by mechanical issues.

One could say that the last driver to retire early after being champion was Jody Schekter, in 1980 - but the South African did it only after a dreadful season with Ferrari, having been champion the previous season, in 1979. One could wonder if Rosberg is predicting problems with Mercedes on the short term?