Nintendo announced there will be a 3D and 2D Mario game for the 3DS but what will it be? For Mario a game on a new system isn't new and 2D and 3D isn't new either.
A remake could be coming like with the DS and Super Mario 64 DS and with Super Mario Sunshine it could be happen. In the world of Mario remakes aren't new there have been several remakes on the GameBoy Advance of the Original 3 in the USA and Super Mario World.
Mario was born in 2D so it wouldn't be unusual so see him return to his roots, games like New Super Mario Brothers and Wii have shown Mario being excellent in the 2D platforming genre and hasn't shown age from the 90's. A 2D game like the originals wouldn't be a far stretch just put in a Super Mario World engine and add new aspects to the game or rather a Super Mario World remake.
As for remakes go one in the 3D department is all good for me since I loved Sunshine, but for 2D that would be a straight no and I would like it to add new Game changers to the Mario series.
I wouldn't mind a sequel to Sunshine, although, I haven't even finished the 'Cube Version yet...[got it in Nov '10, not 10 years ago, xp]
Anyway, If it's gonna be an NSMB Sequel, something in the shadow of NSMB-Wii, I like the Co-Op.
Or, perhaps,[and this is stretching their luck a bit,] a 4th chapter in M&L RPG. It's not a Miyamoto genre one, but it's something to consider... But, it must be SuperStar Saga length, I want a challenge.