he's saying that he believes that the game has reached the limit of characters that can be possibly balanced, then he said that it's not more characters what the game needs, but a change in direction (whatever that may mean)
unless you want him to spell it out, it can't really be much clearer.
and honestly, i sincerely doubt that Ike will be staying. on a business standpoint, they would probably select someone from a more recent game in order to promote the franchise, since the game is essentially a glorified commercial (a very fun one, but a commercial nonetheless) the franchise needs a lord that would attract new fans, and honestly it's easier to do this if their introduction to the series is through the most recent and relevant game/character rather than on a past game, from a previous game system that has already lived its life. and since i highly doubt we'll be getting any sort of new fire emblem in the near future, Chrom is the best candidate for this. As far as Fire Emblem goes, the only one guaranteed a spot is Marth, and that's only because he has seniority.