Well, obviously everyone will convert to Android and There Will Be Only One.
Seriously though, I think we're stuck with fragmentation for many years to come. Some would say that's a good thing, with competition encouraging innovation, and non-homogeneity discouraging security threats.
I do note that all the recent platforms seem to be crystallizing around Linux at their core, including Android. SQLite and OpenGL are available on more than one. HTML/Javascript is available on more than one. Flash and JavaFX are kind of wildcards right now but I have my doubts they will become standard. ARM is standard right now but Intel is investing a lot of money to change that.
Meanwhile, we have to write apps for our users right now, so we learn as much as we can and use what's available now.