You could argue the same for Towa and Fie since they show up prior to Altina. I frankly don't think they'll lock her in as the canon girl otherwise they'd have continued off somewhere from where their final CS4 bond event placed their relationship at. Maybe Altina gets the privilege of being a Rean orbiter and acting like a school girl in love with him, but I wonder if that's better or worse than her fucking off not showing up until the final game where (maybe) you get to choose a waifu. But even then, these characters are bound to pop up again and again even if Falcom wraps up Trails and I really don't think anyone but Estelle and Joshua will get a package deal, but guess we'll see.