Well, considering who her current instructor is...
It would be awesome if season 4 focused around those two.
I'm worried that it might go the other way that they're going to be phased out more and more from now on, though. Tia is much more popular than Subaru, and that has to count for something, but popularity didn't stop them from giving Fate the short end of the stick in StrikerS. (lame poorly developed team, her fight and the fight of her team sans Signum felt like a sideshow next to the Stars Squad's fights, made to look weaker than Nanoha, etc.) Subaru seems to have the director's favor.