A thing I realized just a bit ago was why 5E got to use Neo-Vancian casting for prepared casters. Since the "caster levels" stack in 5E's multiclassing along with spell slot growth, you have a hard time which slot came from which class, and thus cannot allot individual slots to a single cast of spell each. As such, as a side effect, it finally saved Sorcerers from dented slot growth, too.
So I wonder, how will caster levels and Vancian magic function for PF2? I personally prefer Neo-Vancian, as it is super-tedious to prepare spells like individual bullets filled with different viruses, plus PF1 already has the Arcanist as an acceptably fine execution of a Neo-Vancian caster. And as we know that PF2 spells will also now require manual upcasting (plus downcasting, too? I don't have a clue about that), this actually might be what's really happening.
If Neo-Vancian for PF2 is true, I'd mostly be happy, but would also want it ensured to be like {prepared caster's daily prepared spells < spontaneous caster's full known spells}; the former can change spells completely each day on the fly, while the latter is stuck with its choices semipermanently, so a balance issue (5E failed miserably on this one).
So, my morning (UTC+9 here) ramble is finished now. Do you have any other thoughts about this topic?
I'm really hoping that the Arcanist style, what you're calling neo-vancian, is the default for prepared casters and that spontaneous casters are completely different. Something along the lines of the Kineticist with different flavor because it would make them actually feel mechanically distinct rather than a tacked on expansion to double down on a spell list.
Sorcerers don't have a lot distinguishing them if wizards cast like Arcanists. They never had a lot in the first place. I hope they use this opportunity to make them more interesting.
How about Sorcerers being the basic Psychic (/innate, or something else) caster? If the one of the two obscure spell lists do happen to be Psychic magic, I strongly feel it can finally get rid of that awkward V & S components from their (supposed to be) innate spellcasting.
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P.S. By awkward, suppose a creature in-universe that can innately cast real spells (a.k.a. Sorcerer spells), but it has no elaborate appendages nor vocal organs. Yes, it's very awkward to simulate, and naturally it happens to be my greatest pet peeve with 3.Xe Sorcerers...
I like the 5E multi class spell progression, and I hope PF2 does similar.
What I really like is this quote "Prepare spells like individual bullets filled with different viruses" I mean what? Virus filled bullets, where did that come from? :D