A gamecube remake is unlikely until we know three things.
1. What type of System Specs the DS2 has.
2. What type of media the DS2 has.
3. What type of graphics the DS2 can support.
But, frankly, I doubt the game will see a remake for one simple reason. Mario Sunshine lacked the popularity that Mario 64 or even Mario Galaxy has. If you look over all the markets for not just Mario games, but all 3D Nintendo titles, you will see a common trend. After Mario 64 and Zelda: Ocarina of Time, there's a consistent drop off of interest in the Japanese market for 3D Nintendo titles in favor of their 2D counterparts. This would put in favor the idea of them making something more like a 'New Super Mario Bros 3' or 'WarioLand 5' for DS2 launch instead, to try to capitalize on all their markets, including their strongest market, Japan.
Six upcoming games you should look into:
