Woe: Pokemon Stadium 2 is my definite. A lot of the stages I think will get new versions that better fit the new games (such as Luigiās Mansion, Mario Circuit, Smashville, Kid Icarus stages, etc). However, a lot of the Brawl ones will probably return though, including Smashville, possibly WarioWare, etc. Maybe 75m and Mario Bros too as special stages.
Volcanic: I agree about Pokemon Stadium 2, and that most stages will get new variations with franchise updates (like new Smashville, new KI, etc.). Ā If we have to go with 10 stages from Brawl returning, then I can see Delfino Plaza, Pirate Ship, Battleship Halberd, Lylat Cruise, WarioWare, Norfair/Frigate Orpheon, Castle Siege, New Pork City and Yoshi's Island returning, but the only stages I would DEFINITELY rule out are the Spear Pillar, Distant Planet, Flat Zone 2, Hanebow and the third party stages...