People have ALWAYS said "it'll be impossible to top Smash/Melee/Brawl", but it isn't.
Years pass, other games come out that'll be inspiration for Sakurai, other things left in the shadows over the years get put in (He's still missing quite a few Japan only things, even stuff that was released everywhere is still being left out), and so on.
So stop saying you can't top Brawl, because years from now, in the post-PSWii60 generation, it won't be.