I mean if it helps, potentially you could have the characters you want in a DOA game instead of just one guest. DOA4 had Spartan, DOA5LR had VFs+Mai/Naotora which is 6 guests, DOA6 had 2 which is Mai and Kula.
Doesn't necessarily have to be one character so more opportunities, but probably wouldn't want to flood a DOA game with it either. I think 5-6 characters is a good peak max. According to Harada a while back, Kazuya and Heihachi were originally characters that were key elements to be involved in other 3rd party games if other companies borrow the rights:
Project X Zone
SFxTekken
Playstation All-stars (Only Heihachi but Kazuya was mentioned in a dialogue)
Super Smash Bros (Kazuya)
Namco X Capcom
Soul Calibur II (Heihachi)
King of Fighters ALL-STARS
I'd imagine that wouldn't change with Kazuya, and because of recent circumstances with Heihachi's VA passing away, Jin is the one they'd probably go to as the replacement. Since it's DOA, TN and Tekken's team would be smart enough to incorporate at least 2-3 more females. Tin-foil hat theory measure of choices:
Kazuya (mostly because he's a prominent key figure of a representative to Tekken)
Female 1
Female 2
Female 3
(everything else beyond here is guesses with Jin being a stretch due to unknown life support of a DOA game if it includes those characters). Course it's all speculation of a "What If" a DOA had Tekken characters. I hope it happens personally but if it doesn't, eh.. no big deal. With Shimbori over there and his experience with DOA, he's the closest one to making it happen or vice-versa.