Google will probably copy from Wolfram Alpha those things that are likely to be of interest to many users. And it will do so using automated scalable methods.
If this is not all just rigged demoware, then he will succeed, and he's going to make a killing! He will benefit from the same incumbency factors that Google enjoys now, and he'll be a leader in the industry he is about to create.
If it's rigged demoware, he might fall flat on his face.
The important thing to understand is that Stephen Wolfram built Alpha as his personal "publication platform." He is going to use it to in effect "publish" his ideas about NKS and computation in general into immediately useful form, to the entire world. Rather than write papers.
Alpha isn't just some web startup looking for an exit. Its the culmination of a life's work in computation, and the offspring of a 20+ year old company.