Time to catch up with this thread, finally finished the game. Still a lot of story to process and stuff to find, I only really wrapped up the Vantage Points because of the solid storytelling and the nice glimpses they offer into how the world used to look.
I really liked how the story developed ever after visiting the Faro facility. Was motivated to keep pushing on. I was sorta expecting to stumble upon more optional bunkers aside from the first bunker you fall into and the armory. But I guess the Cauldrons functioned more as the optional dungeons. The bandit camps felt a little out of place, felt a bit ripped from Witcher 3 but without the context or background. The game is already top-tier, but if they want to take it to eleven, there's still room for improvement with regards to the in-game economy, towns, villages.. I don't want to constantly compare to the Witcher, but they really set the bar with regards to how the civilized parts of their world intertwine with the wilderness, how monsters and bandits are sometimes part of daily life, sometimes not. The optional missions were more hit then miss for me mostly, though. I think they might do more in the vein of Redmaw in a next game or DLC.
Rost's background seemed a bit.. Vague? By ignoring tribal laws but also going on an heroic quest to get revenge for the tribe, he put the Matriarchs in a tough spot so I get that part of the deal was keeping his mouth shut about his special treatment, but I don't see why Teerza wasn't willing to tell Aloy this right after he died. There wasn't really any pay-off by the time you get to know his story and his passing feels like such a long time ago. I did like the fact that you can visit his grave at various points in the game and Aloy every time speaks about the most recent developments. I visited the grave, for example, right before I headed towards the Bitter Climb and GAIA's facilities.
For sequels, Guerilla has a lot of options. The fate of those outer space missions is one (though they state it failed), there's mention of mining operations on the moon, the after-credits scene with Sylens.. Plenty to go with. I wouldn't mind Aloy heading towards the pacific ocean - sailing and surfing and swimming through tropical atolls, all the marine wildlife that could be inspiration for new robots (whales! doplphins! turtles! Aloy getting her Moana groove on! - I could see them tackle it

. But there's so many interesting options to go from here. Tribes who ride machines or use them for construction, transport or warfare, etc. Oseram didn't interest me that much (bulky pyro-Vikings), but the Banuk were definitely interesting. More lush forest, jungles, mountains and lakes I hope, less desert, was my least favourite region of the game.