We can only truly go about this topic by waiting for brawl to come out.
For now, we are stuck with contemplating exactly what type of gameplay Nintendo wanted for Melee: consider what advanced techniques were probably 100% unintentional-
WD (and all of its variants-waveshine, waveland, etc.), JC, CSDI, Doraki WJ, IC's crazy CG and grab hits, etc. These came about with gamers analyzing melee for every nook and cranny that it has. Gamebreaking? Would this make the game developers cry? imo, no. Its not nearly as extreme as MvC2 has grown to be (what with 100 hit ftw combos and extremely rigged top tiers); they might even be proud that gamers have embraced ssbm as a fighter that is worth such time and effort to conjure up such techniques; no one can really know.
But also consider what techniques were likely intentional: L-cancel (it was in ssb64), CG (comps grab out of ur upB as an edgeguard), SH, FF, [thus SHFFL], shieldgrabbing (the tutorial gives the primary grab method as R+A), SHL (look at the autocancel), teching, the shine(it had the same properties in 64 AND one can assume that, since falco's trophy/figure description boasts his shine as a move that can send the enemy into the air, the shine was designed intentionally to send people downward) etc.
When comparing these techniques, one can see that the current gameplay has come from combining what the designers meant for advanced play to have and what they couldnt possibly have foreseen. Brawl's possibilities all hang on whether the developers like the current metagame of ssbm. I highly doubt that they will throw out air dodging altogether, but if they didnt like wavedashing, they will probably make hitting the floor an automatic cancel of any movement from the air. Who is to say that other aspects of the game wont be explored and abused to the limit?
On the other hand, game creators may embrace what changes the game has taken on the competitive scene; they may just keep the physics of the game the same (or similar) to leave possibilities endless in the fashion that it already is. After all, the input that Nintendo took from Japan on what characters to include in brawl, the smashbros.com updates, and other interactions with the smash fanbase reveal that nintendo cares much about the satisfaction of the fans.
Again, brawl really depends on what the developers want the gameplay to be like. Have they assimilated their tastes to what the current metagame is? or are they keeping a stiff upper lip and trying to create the smash that they intended for the GCN? Only time will tell!