Majin-Tenshinhan on 14 June 2008
Big announcement? Mother 4? You're kidding, right? Regardless of how much some people may like the series, it is far from being big. Either way, they've already said it would end with Mother 3. The reason they added Lucas in was most likely because they said they'd replace Ness with the Mother 3 protagonist in Melee, but ended up keeping Ness since Mother 3 got delayed all the time. So when Brawl came, they felt they should add Lucas after all, but also keep Ness since he'd been there for 2 games already.
Still, my answer to the question in the topic title is "Not very."
