On 3rd parties:
I would like both Sonic and Snake to stick around. Sonic because of massive opularity (I'm not sure why, but he's got popularity). And I would like Snake to stay because he is aslo very popular (Even though he wasn't specifically requested). I know people who bought the game because Snake was on the back of the box. He sells Smash.
New third parties: I would like to see Megaman and a SoulCalibur character. Megaman seems like the most likely choice for a third party. I like SC, and I don't think that a SC character is out side the realm of possibility. Likely? No. But stranger things have certainly happened.
Sonic and Snake are probably going to stay, we'll probably get MM but I'm not sure about SC. You are completely right though, stranger things have happened, looks at R.O.B.
Other Third Parties I want: Black Mage, Knuckles, Shadow, Amy (Face it we'll probably end up getting at least one of those 3), Megaman, Bomberman, and I think that's it.......
I know most of these won't get in, but think about it, they all "fit the requirements". (these are the supposed rules) 1. Nintendo console 2. Originated in a videogame, is that it? The most likely ones are MM, Bomberman, MAYBE one of the sonics, idk about their chances, Black Mage has a good chance because not only did he appear on Nintendo console, it was in a Mario Spin-Off. But again they are all likely but the most likely are Megaman and Bomberman.
Bomberman has history w/ Nintendo if I'm not mistaken and Megaman will get in like Sonic.