Well, according to Lowry, they did just about the best job they could for the amount of time they had (about a month per film). I doubt LFL would bother to pay for anymore cleanup, the only thing they really need to fix is vfx errors they didn't get around to fixing in '97 or '04 (I'm talking matte boxes and the like). Hopefully they'll also realize "okay, the color correction is interfering with how things are supposed to look in certain shots (the lightsabers), we should probably fix that."

As for the OOT, well, the only explanation they offered back in '06 was "existing prints are in bad condition." They could retcon that to mean anything they want if/when they suddenly choose to dig up and restore the interpositives and do 1080p transfers of them.