In short : no.
Why ?
There are more than enough right now. Maybe bring a few more from the GCN game that went MIA since Wild World, but I wouldn't add new ones.
The priority should be to bring back all of them in future Animal Crossing games. The 2.0 version of Animal Crossing: New Horizons sports 413 villagers. If you keep adding more, and more, at one point Nintendo will just start axing villagers because there are too much to bring back every single game, and the dev won't see it as worth the effort to bring all of them back.
That's exactly what happened with Pokémon. The latest Pokémon games started axing Pokémons because there are simply too much. We've all lived through the disapearance of several villagers when Wild World released. Two of my top 3 villagers went MIA for a decade after Wild World (Nintendo only brought them back in Welcome Amiibo!)
Some are still MIA, and I don't want to live through that again.
That is exactly what I don't want.
I actually don't necessarily agree with this. For starters, the Dexit controversy had as much to do with corporate deadlines and a, er... rather transparent attempt to resell a portion of the missing Pokémon in the form of DLC... as it did with the actual amount of Pokémon being overwhelming for a series that is intended to release annually. Not to mention, Pokémon is a very different beast than Animal Crossing. Pokémon is an RPG that requires its mechanics to be balanced for both a single player campaign and competitive multiplayer, whilst the villagers in Animal Crossing have been criticized since New Leaf as being little more than palette swaps of one another. So even if there were thousands of different villagers, I would find it rather difficult to empathize with Nintendo if they started complaining that they couldn't bring back older villagers in a manner similar to Pokémon.
Rather, I think there's something deeply troubling with the philosophy that the games should be built to accommodate for as many villagers as possible. That was always Pokémon's core issue, in my opinion. Its selection of Pokémon, whether old or new, was always dictated by tradition and obligation, rather than how it services the plot, gameplay, and setting of each game. So in theory, I don't actually mind that some Pokémon are not transferrable to later games if it means a greater focus on the single player campaign. Of course, Game Freak didn't actually do that, so I can more than empathize with players who are put off by recent entries simply because they can't transfer their favorite creatures to the latest installment.
If I'm honest, I think a good remedy would be to simply make it so that every new installment has
only new villagers, with legacy villagers only making cameos or only being brought in based on whatever gimmick the next game has to offer. Essentially, rephrase the question from "which villagers will be in the next installment?" to "what type of villagers will be in the next installment?" If it becomes an issue that the number of villagers is so overwhelming that they can't all make the cut and exist perpetually together, then I feel like we're essentially prioritizing Animal Crossing as little more than a trading card game than an actual life simulator.
Basically, I'd rather play a Pokémon game with fewer Pokémon that compliment the overall game than one that is sterile because every single Pokémon needs to be accounted for. Likewise, I'd rather play an Animal Crossing game with fewer villagers but with more memorable interactions and social features, rather than simply praying that my favorites that were abandoned in the GameCube era eventually return. However, that ultimately leads to the question of whether or not I trust Nintendo to deliver that instead of just putting something out as quickly and cheaply as possible. And the answer to that is a resounding no.