Enhancing the graphical fidelity of UT99 would be nice IF the art style remained the same. That seems to be where Epic really fucked up at when they did the later games, including UT3 which looked like it was built using recycled Gears assets. Unreal (and later UT99) was developed to look photo-realistic, but take place in fantasy environments and at the time when CRT monitors generally maxed out at 640x480, it did manage to look extremely realistic when compared to a movie or television broadcast that would be watched in standard (or actually less unless you had cable and DVD) definition. Which reminds me, the closest to an actual successor that UT99 got as far as atmosphere, feel, sound, and visuals are concerned is Unreal Championship (original) for the XBox which was basically everything that UT2003 (which was based off that project, but went a different direction) SHOULD have been.
btw, just to give you guys an idea of how far display technology has advanced, take a look at this game. THE VISUALS IN THE DRIVING SEGMENTS OF THIS GAME WERE (almost) ON THE SAME LEVEL AS A TELEVISION BROADCAST OVER HERE WHEN IT GOT RELEASED!!!