If their platform disintegrates to the lowest common denominator, they won't be attracting developers to theirs at all, just levelling the playing field and competing on ... what? Apple wins at hardware design, which everyone copies, their "metro" design style is much more difficult for users than the other two major smartphone operating systems, and that leaves exclusive content, which just makes everyone feel betrayed or locked in.
Mokalus of Borg
PS - .NET has had a good run as a development platform, I guess.
PPS - But in some ways, it's just getting started.