In terms of the next big coaster what I would love to see is a B&M hyper coaster or a Intamin Woodie.
With the hyper though a B&M would have to go over 150ft at least, and digging a hole for such a ride would be way too expensive. Maybe they would go for an intamin hyper as it doesnt use so much room?
A woodie would be easier to create a good ride experience with less hight but wasn't there an issue with the ground being too unstable for a woodie? Unless they have sorted that with the hybrid models or steel supports/wooden track.
Aside from those two I'd love to see one of the gerst