You know, we ask ourselves this a lot while wandering Disney World. Here is our consensus.
1. Rides like Tower of Terror and Kilamanjaro Safari would blow him away.
2. Some of his originals sure have withstood the test of time.
3. Disney sure is a profitable place.
4. Epcot didn't meet his expectations (although I'm not sure anything would have).
5. We don't think he would have a problem at all with things like FP+. After all, he was always trying to push the technological envelope.