Do you have a link to Sakurai saying that? An interviewer did say that to Sakurai but his response to that was along the lines of, "I am not really sure about that, however, I do think that Nintendo has created barely any new characters in recent years."
Still, practically all the worthwhile characters that deserved to be in Smash Bros. were added in Brawl. The only one left that is really needed is Ridley. K. Rool and Dixie Kong are also well known as well, however, outside of these three, there is nobody left for Nintendo's veteran series that is a recognizable character outside of those hailing from the Mario series.