The problem with the possible idea of Project M as DLC if Brawl were released as an eShop title, is that redistributing it in a new form (even if it's Virtual Console), would require potentially going back to Konami/SEGA/whomever is involved to promote and distribute this. Not to mention with the potential new characters in the pipeline (Ridley, Skull Kid, Lyndis, Knuckles, Isaac are the ones I believe. though Ridley was only rumored while the latter four were leaked).
Knuckles alone as another 3rd party character would cause problems. It's next to impossible without investing so much time into the game. And to be perfectly honest, we're perfectionists and PM goes through so many iterations as it is. How many more do we have to go through? We complained about Sonic (which is legitimate he was really strong against fast fallers, though he was nerfed too soon as well IMO), the team responded and nerfed him. Ivysaur? Same thing. Mewtwo? Lucas? And Nintendo likely wouldn't patch a Wii game that's been out for years, let alone introduce brand spanking "new" DLC in the form of project. It would undermine and cut the original game that was created; no offense to Brawl.
Putting it crudely sorta, keep dreaming pretty much.
[EDIT]
Not to mention that would require removing Isaac and Lyndis from the Assist Trophy list. Not that hard to do, but what about the people that like those characters in the original Brawl? Nintendo can't just cater 100% to the competitive demographic, lending even moreso to the improbability of that idea.
They can support us, watch our scene flourish, support us as we raise awareness for their games as newcomers to competitive Smash or even casual get-togethers play and buy their product. But they gotta turn a blind eye to Project M. If they acknowledge it, they Cease & Desist it by virtue alone.
