I guess I'm just not seeing the game in such a hopeless light. But it's late and my brain is fuzzy and I just can't argue it right this moment. I'm sorry.
Edit : Pehaps a kitty hug instead?

Sorry, I'm just in a terrible hellspiral right now.
One line making it into the game does not indicate a set path for anyone. And Sera doesn't like anyone in power. She also doesn't like elves. Sometimes you have to take what she says with a grain of salt.
Also, puppeteering Gaspard is not always Briala's role. You can put her into power by herself - which I don't see lasting long tbh, not with most likely the entire nobility against her. You can reconcile her with Celene. You can have all 3 try to work together. How any one of these will affect her going forward, we don't know.
And sadly, we maintain the status quo because we kind of have to. If we could wildly change things, BioWare would have to take all of those changes into account going forward into the next game. At some point the worldstates would be so divergent BioWare would almost have to make entirely separate games just to deal with them. Which they can't do. So until the end of the series, the status quo kind of has to stay the same or close to it. I know we all want to make truly world changing decisions but it's just not possible within a series like this where we expect our choices to be reflected in future games.
Sera hates elves more than she hates human nobles. She'll constantly throw Lavellan's "elfiness" back in their face but not human Inquisitor's, and give Elf Quizzy an ultimatum to abandon their culture or get dumped but never does so for the human noble quizzy. But that's okay, because apparently the elves are as bad as she paints them as, and totally deserve it. 
So no matter what happens with Briala, she just ends up in a position where human nobles can pull the rug out from under her or wind up back under her abusive mistress's thumb (and Celene didn't hesitate to use and abuse her before)? Wonderful.
Then why the heck does BioWare sell their games on having "meaningful choices and impactful consequences" if they have no intention of delivering?
So...what would you like to see from the game? Considering that everyone's main plot needs to end up in more-or-less the same place?
Apparently I just need flames rise from this game for all the good is does me.