I hope, for the sake of everyone's mental health lol, that we keep our expectations on track. I personally don't see a lot of features coming back, specially those from NL. I think NH was developed with GCN and WW on mind more than what NL was, so I can see more features from those entries returning over NL.
With that being said, I'm sure plenty of NPC's will return in some form. I don't expect all of them to return as permanent residents in your island but I think many of those certainly will. I can see Brewster returning (as it has already been hinted by data miners) but I'm not sure if he'll return with The Roost as an independent building or an extension of the museum (I don't mind either case, tbh). I can see Redd coming back for sure, along with the return of forgeries and art pieces (as yet, another extension to the museum).
Harriet is a bit tricky. Based on a previous discussion with another user, I think it's more likely that she'll return as an ocasional visitor to the island with either new hairstyles/colors/makeup or (as the other user suggested), cool wigs!
Leif is confirmed to be returning to NH, so far only for Earth day. I like the idea of Leif hosting Earth day because they'll probably add more depth to that event (which was already lacking in NL and previous entries), but I don't think Leif will become a permanent resident. If that were the case, I don't think he'll be selling us any bushes or new fruit. I think he'll mostly give us items related to nature (maybe exterior furniture) and maybe DIY recipes for bush-fences.
Unless they can find an entirely new role for Pete, Phyllis and Pelly, I don't think they'll be returning to the game as updates. I'm bummed about this because they've been around since the beginning and I really liked them as characters (plus their love triangle). However, their role in AC was minimized in NL, imo. Even Phyllis characteristic mean traits were reduced to nothing and as far as I remember, their love triangle story was dismissed. The only plausible reason I can see them returning is, if somehow they'd show up for Valentine's day or something like that. Considering how much NH has been inspired on GCN, maybe they'll make a return of some sorts or maybe, bring Pete back to occasionally deliver your mail personally as in previous games.
Copper and Booker are tricky as well. I can see them coming back as buildings - a la New Leaf. However, I do feel that if they returned, they'd have to add some depth into their characters other than just being another "lost and found".
Kapp'n and Tortimer I can absolutely see coming back. I can definitely see the dock used by Kapp'n to take you to a 'special' island or Tortimer island. Wasn't Kapp'n also in the official art work or merch?
As for previous features:
I don't see Dream Town feature making a return exactly as it was in NL. I can see them, maybe, making something similar. Like, instead of going to mystery islands you can earn 'dream tickets' or 'bizarre destinations' that can take you to other user's islands a la Dream world.
I don't think swimming will make a return. I don't personally miss it, but I can't see this as a very important feature to include anytime soon, tbh.
Multiplayer island is something that I can see return in some format. We might not get an island per se, but maybe they'll add more features to play along in your own lands.
