Don't tell me it's happening...
If this happens, I'm taking it as some kind of abstract sign that they're likely to come back next game.




. . .Then again, it's a no-brainer that the Ice Climbers are going to be among the most requested even aside from standing coincidences.
Out of all the cut characters that haven't been added back as DLC, Ice Climbers are pretty much just beaten out by Snake and maaaayyybe the Trainer part of Pokemon Trainer in terms of the amount of fanwork attention they had while they were in. The Ice Climbers also got a pretty negative reaction to their cut to the point that people wanted the handheld version of Smash to die in a fire partially because of their removal, so at the very least they are seen as valuable to some degree.
Considering the stigma against Konami these days and the fact that not that many people actually seem all that cut up about the Trainer leaving since we still have Charizard, the Ice Climbers could easily become the next Roy.
If the next Nintendo handheld breaks into Gamecube-level capability (which seems possible seeing as the DS was sub-64 but still ran 64 games and the vanilla 3DS properly runs 64 titles), the next console fixes whatever made it so that the mirror couldn't be up on Wii Fit Studio during an eight-player match, and with a little faith and pixie dust on the online function, the IC could very well be added back next game. Granted, that still leaves the possibility of their being pushed to DLC, but it could happen.