Heh, I suppose so. Even if the Chaotix levels aren't planned to be added, I'd still love to see Bomb and Heavy as playable characters. Heavy is legitimately my favourite character from Chaotix. As for who the third team member would be, I think EggRobo or Metal Sonic would fit well. I should probably shut my yap, though. As fun as it may be to gush about what I'd like to see in this hack, I don't want to put any pressure on flamewing.
So, uh, wow... When I posted this, I knew that porting over levels from other games would be a lot of work, but I just found out that Chaotix, in addition to being on a different console (which I already knew) actually uses an entirely different game engine, which was built from the ground up and shares no code whatsoever with any of the Genesis games. If it wasn't true before, it's definitely true now: you'd have to have insane levels of dedication to port all of Chaotix's stuff over to one of the Genesis games. And that's not even considering all of the weird bugs and inconsistencies in Chaotix that would have to be fixed, like the fact that half of the badniks were seemingly never finished. I guess my dreams of marathoning every mainline Sonic game in a single ROMhack will have to remain dreams for a while longer. Oh, but if there are any plans to add Sonic 3&K levels, I had a thought as to what you could put in their special stages. Since in the original game you collect Chaos Emeralds and turn them into Super Emeralds, what if you instead collected Super Emeralds and turned them into Hyper Emeralds? I know it wouldn't make a whole lot of sense, but it's the best idea I could come up with.