"Back to the Future" I think should go into Universal Studios. Kidzone could be easily demoed and transformed into a new land themed to the 80's. It could be done pretty cheaply as well. Universal Studios only needs to really build 1 new attraction to put alongside E.T. and Ghostbusters (a rethemed Men in Black).
As for the new ride, I've been thinking about it for a while. My "Back to the Future" attraction idea would be a slot car thrill ride. And be more similar to Test Track in Epcot than it's previous incarnation. Because the original ride is way too much like it's nearby replacement and also Universal already has enough screen based rides. (Doc) Brownie points if they can make it go 88 miles per hour and blaze fire.