Follow up AGGRESSIVELY in an email. Tell the prof you've had a decision from (comparable but more prestigious) school and, as it stands, you may take their offer in a few days.
Attach a picture of you hugging the prof from the other school, and generally looking like a happy couple.
Make sure you are visible to the prof on some kind of social network, and spend the next 2 years posting about how good the place you got accepted is, how happy you are in life, and overtly imply that they can supply you with sufficient resources that the original prof never could.
Then, in 3 years time, just as you're about to submit your thesis, text the prof that never got back to you out of the blue, tell him how things have been and say how its just a shame how you never got to do your research under their supervision. He'll mention how he has a new, younger student that they are happy to supervise.
At this point, just put your Thesis in his hands, look him in the eye and tell him how desperate you are to publish. He'll be captivated. Spend the next 3 days working like you've never worked before, and then submit the thesis for its defence.
Meanwhile, he'll convince the other student under his supervision to quit, because he only wants to focus on your research work together. The other student will leave in tears. They had good research, but you don't care.
When it comes time, you pass the defense with ease, and better yet, your paper is going to get published in ALL the journals, You remove all mention of the professor from the paper, delete all copies + drafts from his computer, and you get a restraining order on him. You take one of his PC's with you and maybe his office chair because, you used it alot, so its basically yours.
I think that would work out quite well.
