Short answer: yes. Why?
First:
Those who are good at Melee are good because they have been willing to put in time and dedication to practice to better their games. They will likely be willing to do the same with Brawl, and will therefore also be good at Brawl. No amount of "advanced techniques" or "glitches" or "floatiness" or anything will beat out practice.
Second:
Pros are pros due to mental things, not just technical things. Things such as reading your opponent, being unpredictable, strategizing, focusing under pressure, etc. also supersede any changes in game techniques.
Sorry, but you are ignorant if you somehow think that everybody will be the same skill again just because characters fall slower or there's no wavedash.