I would love to see an epic remake similar to SMB3. SMW was a decent following, but not as big and I could tell more time was put into SMB3 then any other mario game (except maybe Mario 64).
I would also love to see Wario and Waluigi finally appear in an adventure game as villians.
My idea was to have a major 3D game made with worlds and make it Bowsers last great epic attack.
Bring back the 7 children from SMB3 + Bowser Jr
Bring in Wart
Have DK Jungle as a world in it with King K Rool as boss and a battle with DK
Make it 4 player that allows you to choose playable characters starting with Mario, Luigi, Yoshi, and Toad and then later unlock DK, Diddy Kong, and Kirby.
Finally I think since Kirby is sinking as a major game (not been Kirby game in forever) make a level called the Dreamland that you will go to after traveling through a space level from SMG (Have some world from Galaxy).
Order of Worlds with bosses
1. Mushroom Kingdom - Wario and Waluigi
2. Desert World - Tryclyde
3. Ocean World - Wendy, Lemmy, Larry Koopa
4. DK Jungle - King K Rool
5. Sky World - Wart
6. Dreamland - King DeDeDe
7. Hill Top World - New Enemy (I want someone not seen yet) or possibly the MagiKoopa from SMW 2: Yoshi (can't remember his name)
8. Pipe Maze - Roy, Morton, Iggy, Ludwig von Koopa
9. Bowserland - 8 Koopa Kids united; then a final battle with Bowser