So he's basically saying there is a possibility for the 3DS version to not get the full roster if there are technical barriers that arise down the road?
Pretty sure he's saying what we know already; i.e the 3DS roster is supposed to be identical to the Wii U despite the possible quantity limitations that Wii U might suffer ramifications from.
With that said he's also reassuring that they haven't hit any character hurdles yet, and if they're launching next year they most likely already have a majority of the characters they want to include pinned down.