I do think Nintendo Land feels a bit random for USF, but I do think they could make it fit if they:
1) Hammer in that USF isn't just "Ride the Movies" anymore, but a celebration of the whole entertainment industry, from movies (almost everything), to T.V. shows (Springfield, Fallon), to books (Diagon), to music (HRRR), to video games (Nintendo).
2) Have some sort of London-esque facade outside of Nintendo Land hiding it from the outside world. This was one of the best parts of Diagon and I think doing the same with Nintendo Land, to hide the fantastical elements behind a city-like environment, would make sense, considering most of USF has an urban feel anyway.