I don't see Vortex leaving the park anytime soon, as for a floorless converstion, I don't think it's going to happen, the station itself is extremely crammed already behind buildings and on top of the park's service road. It seems to me more efficient to just make it into a sit down coaster. It would be cool to see it repainted to it's original colors too.
What I honestly want to see is Demon with new coaster cars, preferably the new Vekoma lap bars with the stadium style seating, and just an overhaul of the general theming like replacing the lights in the tunnel, bringing back the foggers. etc.
Couple of places to put a roller coaster:
-Remove Psycho Mouse and the Go Kart track for a small Euro-Fighter, it would provide more square footage than the Inverti-Garden.
-The perimeter of the rapids utilizing the old railroad right of way for a launched coaster would be cool too. It's actually really scenic back there, the railroad trestle is still up and so is the water tower, would make a really good mine themed/railroad launched coaster.
-The Greased Lightin' station is still up, could always put a Wicked Twister/V2 Inverted launch Intamin.