While I don't know if Melee getting in will benefit Brawl, I at least know that it will benefit Smash 4 when it comes out. If they see how well competitive Smash turns out for them, they'll be more willing to give Smash 4 a chance when it comes out. And that's why people are saying it will benefit the Smash community and not just Melee. The Brawl vs Melee argument isn't black and white. I started out loving Melee, fell in love with Brawl before its release, slowly lost interest as it went on, and developed a love for Project M. Regardless of whatever rumors and speculation that Smash 4 will be similar to Brawl (I'm preparing myself for it too), I'm going to give it a chance when it comes out. And just like what happened with Brawl, everyone but the most hardcore Melee players will switch over to the new game to try it out. Brawl players, Melee players, even 64 players will be lining up to try out the next generation of Smash.
And maybe it won't be exactly what they wanted. Then in that case, they'll switch back to their favorite game and no harm done. And maybe through Melee, EVO will see how hype competitive Smash can still be when you're not using a bull**** ruleset like the one they forced on Brawl in '08. And because of that, we'll get the tournament we want with Smash 4. So remember. A vote for Melee is a vote for Smash 4.