I liked Brawl, too. I understand being disappointed, but personally, I can't really compare it to Melee. Even back in 2008 it was impossible to recreate the environment that made Melee what it was for me and my friends. What little I played of Brawl was fun.
My concern with this Wii U one is that it'll be more of the same and become "another one." The hypothetical version of Smash Bros Wii U that's Brawl with better graphics and more content is not something I'd want. Maybe if the entire game is rejiggered around online play, or there's a neat gimmick to the single player (RPG-ish like Tobal, kumite with costumes/items).
And I want the 3DS one to be a 3D arena fighter, Power Stone or Gundam vs Gundam style.