i can write a book about the subject, so i'll get to the point:
the success and widespread of a platform (silverlight, flash etc...) is a direct result of a major success in terms of $$$.

Web applications rose beacuse of individulas like Amazon.com who made ridiculous amount of money, thus, creating a massive wave of followers (followers that wanted to capitalize the same way).

it is the same as Reality TV: it existed for ever as game shows and others but it took "Survivor" to create a mass widespread of the format.

IN the END Technolgy becomes widespread if you have a croud of followers (follwing a massive success).

SO, if i were Microsoft (or Adobe..) i would have to create a cross platform enterprise who created ridiculous amount of money (in a Dummy Sub Start-up)!!!

you can't just wait for it to happen on it's own...