Microsoft has already promised upgrade paths for new wp8 phones, so it seems like the problem is just google now. I'm ditching the iPhone soon- iOS 6 is infuriating to me, and I'll probably go with an android, but the lack of google support is part of the reason I'm waffling
Your best bet then is to go with whatever the current google phone is. Right now that's the Galaxy Nexus. Stock android, updated regularly, no carrier or OEM bloatware.
