Nice hypothesis. While I haven't looked into it with any great detail it's not unreasonable to say the hype's going to die down. If they are not kicking tangible goals, being open (within reason) on their development and delivering effective value in some way then it will be struggle in the shorter to medium term. And yes, how on earth will they sustain that value in the mean time.

So many parallels with the dot.com boom which suggests many big failures to come, but out of it some sound business practices. The big questions is obviously, how do u pick them?