just a thought on who would have got Lewis's seat at Mercedes if he had chosen to stay at Mclaren and any knock-on effects it would have had.
i think its safe to assume Button would have stayed at Mclaren so Perez would have either had to stay at sauber or move to a different team if he stayed we may not have ever seen Hulk at Sauber or Gutierrez. but he could have just as easily gone to force india a year sooner than he did.
looking at potential for the Merc seat the best i can come up with is Kimi. a top driver with name value something they want. only at lotus at the time but getting good results. i can't remember his contract situation at the time but if he was tied down at lotus until the year he moved back to Ferrari. then things get difficult for them having to either pick a rookie or convince Michael to hang around another year. all the other top drivers where at teams chasing the title and not particularly fed up with there teams like Lewis was.
saying the didn't get Kimi for 2013 and picked a rookie any best guess as to who they could have picked up and how they would have compared to rosberg in the new era nothing else changes in terms of car performance just for fun who do people think would have had the chance to share titles with Rosberg and if they would have done a better or worse job against rosberg. i happen to think kimi would have drawn 2-2 with rosberg and retired on 3 titles total last season