It is a question of comparing bananas with bananas and apples with apples. (No pun intended.)
Android is growing as other manufacturers switch their OS to it. These same manufacturers are loosing market share to Apple. Android will continue to grow until all manufacturers that don't have their own viable OS have migrated. How much market share these manufacturers will hold in the future against Apple and Blackberry (perhaps HP in the future?) is the real question.
No one manufacturer may top Apple individually, and it won't matter. The precise reason Android will grossly outsell iPhone in time is that it will have the collective R&D and marketing and carrier biz-dev of every major manufacturer but one.
It's a perfect repeat of what happened in home computing and it will end the same way. And just like there, Apple won't be too pissed because they'll still make a fortune. Owning the high-end 5% of a market is sometimes as good as (or better than) being the dominant force in the other 95%.
Android is growing as other manufacturers switch their OS to it. These same manufacturers are loosing market share to Apple. Android will continue to grow until all manufacturers that don't have their own viable OS have migrated. How much market share these manufacturers will hold in the future against Apple and Blackberry (perhaps HP in the future?) is the real question.