Hamilton is worth a lot more than the German tie in. The car is the car, that is all that matters. They need to sell Mercedes cars in Dubai and the USA, China, not just Germany. In fact Germany is likely a small market for them. It's not like the german GP was the best supported of the season and Hamilton has more support worldwide at races. I don't know why they people think having a german is important.
In fact, an all German team with a potentially all german line up really doesn't do anything. These companies aren't about a single market, it's about mass appeal, worldwide appeal. Hell a german car, german sponsor and two german drivers might play great in Germany, but could be negative in terms of worldwide sponsorship/appeal. It's not exactly like if they have no german driver people will forget Mercedes is a german brand.
If it was Schumacher, with the world wide fan base he had, with say 3+ years of driving left, then maybe. But Rosberg, a guy being pretty easily beaten, who is clearly the slower driver who doesn't hold a lot of German or worldwide appeal?
I was mostly pointing out that the automatic idea of getting rid of Hamilton over Rosberg is silly, not that it is truly likely they would get rid of one of them.
However, it's not a rare occurrence for a driver to move on or be moved on when the team isn't getting along. It's certainly well within the realms of possibilities.
We'll have to see how the season goes on, think of it this way, if Rosberg sees the title slipping away, Hamilton likely to stay and his chance of winning a title in the next few years all but disappear.... what exactly does he have to lose by knocking Hamilton off again. Maybe he wins a title, maybe Merc get rid of him....... but then he gets to be the champion, he gets to win and he'd get champion type wages at his next team. What exactly does he have to lose, being the second best driver at the best team for multiple years over sneaking one title and basically being fired? That is one more title than just being beaten by Hamilton.
Of course Hamilton might have crappy luck and lose every race from now. But if it gets tight, and Rosberg has the chance to nick the title, who knows how he'll react. He's already reacted badly on multiple occasions as he sees the title slip away from him and as he gets beaten race after race unless Hamilton.
Rosberg also got a pretty public spanking, who knows how he'll react to that, be as good as gold or will he react under pressure again closer to the end of the season. Certainly will be interesting to see what happens. Might even be disappointed if there is no more drama