Well Last Round has Naotora, that's a start. I 100% would not be surprised if DOA6 added another Musou character like Wang Yuanji or even a Gust character (low key hoping for Arnice or Reinhardt)
Ohh you mean purely tecmo? uhh probably not DOA and Ninja Gaiden is literally the only Tecmo IPs that gets used.
It'd be better for 3rd party outside company characters within fighting genres. Better worth the cost and more exposure etc. There are quite a few people in my area who played DOA because of Mai and they actually stood by the game.
Preferably, I'd take 1-2 Tekken characters in this franchise to trigger both sides of the community in a more positive note.