I was a bit slow to pick up on this.
WOW. So, Hamilton is going to Merc.
Clearly, Merc are not happy with their current driver line-up,s o the weaker driver (MSc) got the boot.
Personally, I think it might've been better to give Rosberg the boot, as he may unsettle Hamilton a little.
We've all seen that when Hamilton is the main focus of the team, he does extremely well and destroys his team-mate in the process (2008/9). However, when the team-mate is decent and the team do not give him outright No.1 status, he tends to get unsettled (2011).
Had they kept MSc on, Hamilton would most likely have scored double or triple MSc's points total, hence, Hamilton would've seen MSc as no threat. However, because Rosberg is a better driver than MSc, Hamilton may not have it all his own way (similar to when he had to go up against Button, who beat him in 2011).
In any case, the above is all speculation and conjecture. What we do know is that Hamilton will get a fresh challenge at BrawnGP. And R.Brawn, for the first time since 2006, will be working with a top of the line driver (excusing 2009, which is arguable).
So Arknor...what next for MSc? Any back-of-the-grid (or even mid-field) team (Sauber, perhaps) would be happy to have him, due to the money he would bring to their team. Do you see him continuing to drive in F1?