Siri and the iPhone 4s is nothing new, Apple simply tied a lot of things together that already existed and added a bit of shine and sparkle.
1) The iPhone would become the new dominant computing platform. 2) There would be a dev kit for more tightly integrated applications. 3) A Siri equivalent would be on the iPhone, possibly delivered by a startup or Apple itself. 4) That this would be happening soon, in a subsequent version of the same device, or I would build it myself.
While this isn't magic, it is a pretty good prediction, and a lot more specific than what you just stated.
Finally, if this was all so obvious, why didn't anyone else predict it?
>"1) The iPhone would become the new dominant computing platform."
By what measure?
>"why didn't anyone else predict it?"
Absence of evidence =/= evidence of absence.
The original iPhone was nothing new component-wise but something wonderful is summation. This has been Apple's gift. Lots of folks can dream up and write a paper about super-phone, it's a top-notch engineering company, living in the real world of engineering trade-offs, that can actually build and sell millions.