Diversification of Mobile Platforms today is killer of mobile developer's productivity (& profit). We are forced to choose a platform and stick with it - I guess this will start becoming a common place & the best platform will eventually win. Many developers will only focus their efforts on one platform. Btw: It already started happening.
I am more than happy to support any platform which comes to play. So long as I can find developers for the given language needed for the platform, the platform is standardised (eg. Java) & deploying/porting the app to a platform does not involve rewriting it from scratch.