I think Pac Man has really high chances of getting in, as he should. He is an icon of gaming and the mascot of Namco, even if they weren't developing it i'd still be expecting him. Any body that references his Street Fighter X Tekken appearance where he pilots a Mokujin should remember that Megaman was chunky and from his bad box art in that game, those appearances were joke guest appearance and you shouldn't take those seriously. For moveset potential look at the Pac Man World games.
*Even with that Sakarai can easily come up with one
As for Lucina, after Little Mac was confirmed she is now my most wanted newcomer. I think she is much more interesting than Chrom. However, her chances are pretty low due to her similarity to Marth. I really want her as her own playable character, but an alt skin wouldn't be bad either I guess...
* If an Alt skin, it still be her. Im not talking a small costume change like Peach~Daisy!!!
For an e-shop rep I would much rather have Mallo from Pushmo than Dillon. Wasn't Pushmo a more successful game overall than Dillon's Rolling Western? Dillon has rolling into claw combos, which could be similar to Sonic in a way, while Mallo could bring a whole new fighting style to the mix: Sumo. He could also push blocks around and hit a reset button for a final smash or something haha. Also I'm pretty confident that Tempo from Harmoknight will be an assist trophy so he could replace Jill from Drill Dozer (:L)
*Yes Pushmo technically is bigger than Western Roll
I think Geno and Krystal's chances are slim to none. The days where they popular and had high demand are long gone and they are supporting characters, not main protagonists/antagonists, which also lowers their chances a little bit more.
* They really have dropped, but maybe there's hope?