Nice observations concerning the player character. It surely is still mysterious, and it'd finally make for a game in which the whole "you're no ordinary trainer, are you!!" comes back all the way round.
There are also implications that the events are of a cyclical nature, though I've seen enough of that kind of story in the past decade. Post-game might be a "what-if".
I was expecting to see Titania on that list somewhere, given that she's been a big source of misery for at least 50% of her supposed high school clique
(Julia still seems very "shallow" (as in, -actually- untroubled too much?!) in comparison to the other three, which just might be her exact thing all the way through to the end? it's telling they haven't had any actual interaction yet),
and 50% of the time killed someone specific in blind rage, and 100% of the time killed a lot of people in blind rage,
and there could be some sort of "atonement" (she's not particularly blind to what she does, but it'd be disingenious character development, since she's already been moving... somewhere into a whole other direction) for the folks who appear like they actually should be her friends (yet she could manage to cut them down one by one somehow), in one of those heated moments in which she just seems to falter in. It's still her turn to really do something "good", a flicker that there's an actual heart beneath the steel.
...though I'm sure the most likely scenario is that she'll find a way to blame everything on everyone else and then skedaddle the hell out of there cuz it's just "too much trouble" to actually work things out.
Solaris/Taka (if both still alive) might be in a position to show just that. Though I'm afraid one of them will pay with their life for it, or both independently, though that'd wipe out the genetic line of known guardians (where's El been at?).
Solaris stands strongly behind his viewpoints, yet as his ways cost him everything and don't work on top of that, I see him as the type of character that can really think things through to another end.
If Sirius doesn't simply turn off the lights for him, I can totally see him getting through.
(...There's actually an odd point about him not directly related to surviving, that is, when you meet him when freeing Victoria underneath the Grand Stairway.
I faintly remember his dialogue implying/saying that he'd be cool with everyone knowing about the holy site, that the player should even tell people about it.
That's an idea he never seemed to have tried? Like, just go to city managament, "Hey, there's this awesome Arceus temple down there, I'm in the bloodline of its protectors, don't do dumb shit (again), and we good".
Given that the late city management could have been expected to be quite cool with it... It's certainly nothing the story was ever meant to consider, but with all the animosity he creates, it feels like he missed out on some steps to reach his goal in better ways. Then again, actually talking to people has always been frowned upon by humans, it's just better to insult them and kick them out of places you perceive to belong to you, etc.)