No idea, to be honest... As much as I would love to see Ada, she has no connection to the story (neither has Claire, but when do we ever see her otherwise? She has become the female Hunk). Maybe Jake? He must have been rather young at that time, but we know from his biography that he became a mercenary as a teenager, and it would be interesting to see him like that.
I guess Hunnigan would be nice too... But after that missed chance in RE6, I don't think it will ever happen. Chris is already there anyway, so if they add Claire as well, I think I'll be happy.