Multiplayer?

Even the site states that the game will be only one player, plus as you said the Paper Mario games have never had a multiplayer feature. I'd say there's a 0% chance for this game.

I can't even imagine what would work with a game like this. Maybe a sticker swap..?

I don't mean to rag on anybody's idea, but a sticker swap sounds like a completely trivial thing to include in this type of game. Yeah, it might be cool to be able to acquire stickers sooner than you would through normal progression, assuming there aren't any restrictions to what you can trade, but at the same time, why? I would probably try to try it out once, just to see, but beyond that no.

quote A Person

I don't mean to rag on anybody's idea, but a sticker swap sounds like a completely trivial thing to include in this type of game. Yeah, it might be cool to be able to acquire stickers sooner than you would through normal progression, assuming there aren't any restrictions to what you can trade, but at the same time, why? I would probably try to try it out once, just to see, but beyond that no.

Appeal to kids. That would be one, if not the main reason they would do it I think. It would seem pretty pointless to me as well and probably only used a few times.