What the title says. This is all of course completely wild speculation, but hey, why not.
Firstly, ancestries and heritages
So, the first thing I wanted to consider is the way the planetouched/geniekin/changelings, dhampir, and skinwalkers could work. Namely, in addition to the standard stuff I'd like to give them some kind of feature that lets them pick an ancestry/heritage that they count as for the purposes of taking ancestry feats, since I've always felt like they never got anything from their parentage or upbringing, I feel like an elven aasimar should have the option to draw on the elf part as well, for example.
Another invariable topic is playing as more powerful creatures, minotaurs for instance. The way I see it, this could be gone about in a number of ways. Givning out ancestry feats that are way more powerful than those given to others seems really wrong, but I could see giving them the option to take special "paragon feats" in place of standard class feats or as a kind of multiclass path.
Now to some thoughts on classes
The champion has potential for lots of cool stuff, I know one of the devs (I'm sorry I can't remember who) said they feel its likely all alignments will get an order eventually, but I would pose that we could also see multiple orders per alignment. Kind of obvious, but just spitballing.
The hunter, inquisitor, kineticist, magus, medium, mesmerist, occultist, oracle, psychic, shaman, spiritualist, summoner, and witch all feel like they should be their own thing(s)
The next idea I had for at least some of the hybrids is some kind of feat that you would take after multiclassing to bring together features of your base class and whatever you've multi'd into, which I feel covers the arcanist, bloodrager, brawler, and skald
The slayer and ninja can just be wrapped into rogue paths. much less confusion than 1e
I know that some people feel like the investigator should just be a rogue path or something but I'd really like to see it be its own thing, what with the Int based combat, and I'd personally like to see them as the class who's picked up lots of little tricks here and there, a little alchemy, a little magic, some fighting skills, any combo really.
So another one where I've seen a little discussion is the vigilante and gunslinger. While I agree that they both got archetyped into most other classes, or vice versa, I have to disagree with the idea of them being just a generic archetype, since, unless something changed since the playtest you couldn't have an archetype at level 1, which both classes feel to me like concepts you should be able to start as.
Another shot at the shifter would be appreciated, beyond just a more appealing kit, I'd also like to see an expansion of fluff, mainly make the druidic paladin idea an option, but also have the option to be mad science, lycanthropic blood etc.
I'd like to see cavalier stuff broken into two, one part mounted stuff, most likely a general archetype, and then the teamwork/banner/combat leader thing which could be an archetype it could be a class, I really don't know, similar thing with the samurai (alt classes and all)
I'd don't really know what to make of the swashbuckler, the grit/panache/luck thing feels like it could be an archetype or a class, or just a path for some classes.
With the champion existing and a warpriest cleric path confirmed, I feel as though the warpriest is pretty much dead
Some extraneous stuff
First, I've never really understood why the archaeologist was a bard archetype, but I feel like it could go general in 2e
more/better dragon/monstrous mount/companion stuff. Feels like class feats for classes that get an AC
Yeah, I got a little long winded, but if you made it all the way here, thanks for reading, and I look forward to your wild speculations as well.