Well, they don't have to make it Prisoner 849, there are a ton of other victims on Na Pali that can have happy-ish endings. Or base another Unreal on Na Pali in the future, or even in the past.
Please, if they want to do another game, don't have them use the same ideas we've seen for 11 years (and about 95% of custom maps). I want something new, with underwater skaars against merc submarines in the waters of a forgotten planet named Galimo where the player takes part of a large scale conflict with rocket-boots that shoot razor-blades out of their eels and a nuclear belt that casts fire underwater when sharks are approaching.
Or something equally as badass.
As for Unreal HD, I'd be enclined to think of it as the Half-Life : source of Epic : same game, same weapons, few new stuff and only a handful of reworked models and textures.
You must construct additional pylons.