I really liked Lucas's addition in Brawl. I was actually really rooting for him to be in, playing Mother 3 around the time to. So, yeah it'll be a major bummer if he's gone. But it would be worse to lose Ness at this point though. If a sacrifise has to be made, I'd rather pick Lucas over Ness, even if the choice is bad. Am sure hoping Lucas indeed shows up as DLC. And I think a lot of semi-clones actually might become DLC.
Lucas, Squirtle, Ivysaur, Roy, maybe even Dr.Mario very well could end up becoming DLC characters. Mewtwo to, if he's not in. Other semi-clones I think are possibily are Dixie Kong and Lucina.
Doubt this will be the end of Lucas. Am hoping that his DLC character will somehow be coupled with a English-translated Mother 3. Nintendo is reaching out to it's core fans more it seems, having contacted top Smash players. I could see it even possible that they will contact the guys from Starmen.net and translate Mother 3 officially.