It's a pity that Samsung and Sony would have to fear U.S. antitrust law if they did the obvious thing to respond to Google here: set up their own app store, so that two manufacturers at least - others could join - would be behind it. For their own fork of Android.
Of course, that would still be a risky move.
It's too bad this comes too late for another possibility to be realistic: for Samsung and Sony to license the BlackBerry OS, thereby saving it from oblivion. (Microsoft, of course, doesn't believe in its own phone OS, and I wouldn't want to see them dominate this new market, but that too had been an alternative.)