1. Sonic loops
2. Rideable mounts (Think Yoshi or SML or Metal Slug tanks, subs, and planes)
3. Vines (Typical ones, ones that come from blocks and swinging ones like Pitfall or Castle of Illusion)
4. Enemies (At least boss) to able to drop a magic crystal (like castlevania) or key or card or something when it is beat.
5. Able to set hit points on enemies.
6. More powerups (Raccoon Tail at least)
7. More enemies (SMB2 Sparks, Boo Ghost, Thwomps, and unique sonic enemies)
8. More Bosses (Dr Robotnik, Birdo, Boom Boom, Swoop, koopalings, robo, etc.)
10. "breakable" tyler option, for when you need more breakable block types.
More Characters that were mascots and that have different abilities - fighters, shooters, etc.
These are things that I think would help the game have the potential to create a larger variety of levels. Well that's it. Even if we never get a new version, SB 2.0 has excellent potential for about anything you want to throw at it as you can add code blocks and charms.