When the 4k UHD release inevitably happens, the prequels will be released same day as the OT and probably packaged with it just like the “saga” was back in 2011.
You can count on it.
Being stuck in 2k hasn’t stopped all these other movies from getting released in 4k. There’s even been at least one movie that was shot in 1080p like AotC/RotS released on 4k (Resident Evil: Afterlife).