Yeah, I don't expect it. But there's always hope. And being on the tail-end means Nintendo needs to focus on selling to the existing userbase, which makes DLC a relatively good idea.
Tekken 7 is scheduled to get several additional fighters as DLC as well, but then that's a PS4 title.
Honestly, the best we could hope for is free DLC via patches. From my understanding, the Tekken team (Harada specifically) doesn't like doing traditional DLC in the sense of sticking a price on content and selling it. They like simply doing it for free via patches. And as far as we've seen, the arcades for Pokken haven't stopped receiving updates so it's possible they have long-term support planned in the form of patches based on how well the game sells.
We'll have to wait and see. I don't see them merely vaguely saying there's currently no DLC plans as a complete denial of all support for it -- it would be incredibly stupid for them to never patch the game if it's going to be at tournaments. Who knows what people will find with any character and such. There hasn't been a fighting game in recent years that didn't get patches whatsoever post-launch. Not even Smash, a game people thought wouldn't even get balance patches, could escape getting patches.