I can't see Android going away real fast, or at all really. Symbian went West simply because it didn't stack up against iOS and Android, even if it did against RIM's OS (which I don't believe it did). And Android really has taken hold because of its availability across manufacturers and handsets, variety of choice is out there to that very fickle public that will refuse to listen to why they should all have iPhones instead

It remains to be seen how ICS scales across smartphone and tablet. Will it do for Android what iOS has for Apple? The jury is out at the moment but 2012 should answer that particular question.

Interesting to refer to enterprise, that is going through the transition away from RIM. Some are gravitating to iOS - and it does Apple no harm that the US government and military are also, giving that OS a massive shot in the arm. Enterprise is likely to follow. So Android has got some distance to cover if it is to put the brakes on that happening.

At this stage I don't think that Windows Phone 7 is even in the vaguest of imaginings in respect to the very enterprise that it has abandoned at this time.