I disagree with half of what you said. iOS dumping Maps, etc only puts Google's mobile strategy at risk if you assume that some day iOS will be the majority of phones and I don't think that will be the case. In fact quite the opposite will be the case where Android is the majority simply due to the amount of selection available. Android may not be the greatest thing out there (I am not a big fan though I have one), but if you can't afford or don't want to pay for an iPhone, Android is pretty much you're only other option at this point.
Facebook doesn't have to make money with ads like you said, but I'm not sure what games being integrated with Facebook have to do with it? Unless you have to use FB credits in the game, they don't make any money off of a game sharing your high score. I am not sure the numbers on in-app purchases through FB, but I personally never use them as I feel its a complete rip-off and feel that most would ultimately feel that way. And your reference to Metallica is good, but if Metallica has a web page, they aren't dependent on FB at all, or G+ or Twitter for that matter, and can change social networks with the times. In other words FB is where you go for Metallica news today, but there is nothing stopping it from being somewhere else.
The same point about FB being what's hot now is valid about Google search as well. I do agree that Google is essentially where MS was 10 or so years ago. Google is much more agile than MS was at that time though so putting out a less than popular product (Windows Vista) is less costly for Google than it was for MS. But the point is valid and Google should be very careful over the next few years. Though it should be noted that all companies fade out of popularity eventually.
The big difference is FB essentially serves one purpose (sharing) but Google has search, email, maps, etc. If FB can grow in that way (aka trying to become Google) they will be more likely to succeed. Hence, +Mike Elgan