two things...
the developer who has a killer app idea will develop, somehow.
it's usually not the ppl working from 9 to 5 who do those kinds of apps, but ppl who know who to cross compile, use an emulator or a compatible device...
"Talent hits the target nobody can hit, and a Genius hits the target nobody can see"

but i don't think that a killer app will create a market for a device.
no matter how good an app, if ppl don't want to buy the device, the app won't make them.