This time around I'd like to believe that Sakurai is only cutting characters for very good reasons, and that he wont just get rid of them because he feels like it. He's stated that he knows every character has its own fanbase, and is trying to make sure he cuts as least as possible.
For example
Squirtle/Ivy/Pokemon Trainer - Most likely cut due to the cut of the transformation gimmick, the spot was given to Charizard instead.
Snake - Most likely cut for being a 3rd party. Things didn't work out w/ Konami and it didn't happen.
Now, can we find any other incredibly good reason to cut any of the other characters?
Lucas/Wolf/Falco - They're clones (not really wolf) but that didn't stop Toon Link from coming back.
ROB - Nobody really liked him, but his moveset is fine and theres no reason to cut him
Jigglypuff - People consider her unpopular and irrelevant, but theres nothing making it impossible for her to be in the game.
Do you see the connection I'm making here? I'm basically stating that I think the only chance a character can be cut this time around is if there is something that is making it IMPOSSIBLE for them to return.
So this is what makes me worry about the Ice Climbers in particular. Wasn't it stated somewhere that Sakurai was having trouble putting the Ice Climbers on the 3DS? I dunno, I mean imagine 4 Ice Climbers battling on the 3DS there could be problems with that.
Now, don't confuse me as Im not stating that the 3DS can't handle them as a solid fact, I actually don't know this but I've just heard rumors. But, if it was true, there would be your reason as to why they were cut. If the 3DS CAN handle them, then they should be back without a doubt.