I'm not too up to date on this stuff, but in the past how have these buyouts and mergers faired? As I said in a previous post I really am intrigued as to how the Google and Motorola and AT&T and T Mobile scenario will play out.
From what I read, Google will treat Motorola as a separate entity. Motorola will have to make a bid for the next Nexus, just like other companies. This probably means that Motorola will have autonomy with the mobile hardware side of the business.
As for AT&T and T-Mobile merger, I don't want to venture a guess, as nobody knows the outcome of the merger bid.