I'd like to see Snake Mountain get a release but there is no way I would pay more than $250 for it or any other playset. I'm a huge Star Wars fan too and I still haven't even purchased the BMF yet.
If they can keep the prices reasonable I'd like to see Fright Zone/Slime Pit, Point Dread/Talon Fighter, 200X Slime Pit than can attach to Snake Mountain. For Eternia I would be perfectly content with it being facade pieces.
Some diorama pieces would be cool too. Skeletor's Throne and Table, Zodac's Chair, Zodak's Weapon Rack, & Royal Thrones.