Mario hasn't hit his peak...none of the characters have and aren't even close. The game hasn't even been out a year yet and we're talking about the end of the rope already?
Here's how improvement in smash bros usually goes:
-You practice, play against "good" players, win consistently, then get a big head.
-You take your game to a tournament, and don't even place. Good players violate and embarrass you. You're sad.
-The breaking point, where you either quit or really get better.
-You repeat the process, improving after every tournament loss, till you're M2K. All the while, new ATs are being discovered, tier lists shift, and new guides are created.
We really can't have reached the peak already. Brawl doesn't have as much depth as Melee, but it has enough to last at least a year.