I wouldn't call New York the "Jimmy Fallon Land." I wouldn't call Hollywood the "Bourne land." I wouldn't call Epcot's Paris the "Ratatouille land." I could go on.
Seoul would be created as an eastern anchor, similar to other city based lands at USF (with London being the exception). As I mentioned, they could easily add IP that would fit with this general geographic region. Kaiju, giant robots, martial arts, cyberpunk / futuristic themes all could work for a Seoul land, in addition to the aforementioned anime adjacent and eastern pop music properties. Avatar The Last Airbender, Pacific Rim, and many other IP which reference eastern culture could fit there as attractions. (If kids aren't criticizing K-Pop Demon Hunters for not being genuinely Korean, I doubt they'll have any issues with other IPs in this land.)
With the entire land not relying on the success of a single IP, they could change the IP of the attraction(s) as needed without having to demolish an entire land. This idea relies on Universal building a really cool non-IP land, instead of going all in on a single IP.
I'm not saying this is my top preference, but the reasons this doesn't work really comes down to A) a misunderstanding or misrepresentation of the concept ("splitting hairs"), B) assuming Universal will never build a non IP focused land (which is likely true), and C) business deals falling through / not getting appropriate IPs to tie into the land (which is also valid).
My preference would probably be Tokyo, with the same general concept of non-IP based city with blockbuster style attractions. But I've seen that suggested already, so I thought I'd offer something fresh instead of arguing about the merits of Shrek for another few pages.
As far as the K-Pop Demon Hunters IP itself: Universal almost surely agrees with the rest of this forum... Too early to build an E ticket. But I think the IP is worth keeping an eye on. Yes it's early for this IP, but we're also talking about rides/lands that might not open until the 2030s.