Wouldn't bet so much as a dollar on Wavedashing's return.
Regardless, at worst, Smash 4 should be competitively better than Brawl (unless somethin' truly horrible and unexpected goes wrong). My faith may yet be rewarded.
L-Canceling is an absolute must. The lack of L-Canceling is what made Brawl have such a camptastic metagame. Most (or all) aerials unsafe? No approaching unless forced to via projectiles.
Aerial mobility is another immense concern. Dodgin' projectiles by jumpin' punishes characters with bad aerial mobility, which is retardedly unfair. 'Specially for the heavy and the projectile-less.
Melee-level hitstun is a given.
Wonder Red from the wonderful 101 would great choice for new character,
but we do need more female characters how about Lyndis from Fire Emblem
waluigi would great choice new character