If the devtools could eventually allow it, it would be great. Even if they considered it for SMB2 (If they ever make a second, I assume they will) I would be pleased. I don't feel like SMB was designed with multiplayer in mind, so it's hard to say.
Nnnope. Team Meat feels that a sequel would be nothing but a cash-in and tarnish the original.
..I disagree, but that's what they've been saying.
As for multiplayer: It doesn't need to be limited to time trials together. Think some.. minigames? Like collecting bandages or levels that scroll, pour in obstacles and make the game about survival. Last player standing wins. Or maybe a "get the crown" kinda thing, one player keeps an object away from everyone else.. Then there's straight-up tag, etc. Levels could be designed to compliment them
Game has a lot of potential for some fun & accessible multiplayer