Why, if she's in Solas's body, would she (they?) need to grow anything at all? XD
Speaking of Solas future romantic stuff, I do hope our Lavellans aren't just.... swept aside with a line or two in the future games should ah, what did you coin them as, Badonkadonk? Solameth? XD be involved. Could be interesting to say the least. Off topic, though, whoops!
As for the notes, even while I consider them accurate, I don't know if I count Flemeth out of the running yet. I mean, she's had fail safes before, and Mythal survived murder. Maybe Flemeth is dead now, but Mythal? Ehhh, I dunno, I find that doubtful. Plus dev notes are usually vague summaries of the scene itself, simple words to get the point of the scene across accurately. That doesn't mean they take all the writing team's future plans into consideration. While that could be what the devs wanted the players to assume was happening or take from what was going on onscreen, that doesn't necessarily mean they won't write themselves out of it next game. They're interesting and they certainly add some weight to the Solas-dominating-Flemeth side of things, but I wouldn't call them irrefutable... yet.
You don't even know what it is but you've written it off in favor of headcanon. Why not headcanon the Inquisitor into the Warden? Or Sera into Divine?
Playing the devil's advocate here a bit (heh, no offense meant, Roly Voly, of course), buuut I believe what they're saying is that they takes into account what is confirmed in the lore and shown solidly in game. Anyways, nothing wrong with skepticism! So long as you're not making yourself miserable, anyway. ;D