I doubt they ever do a 4K remaster. They are going to continue to repress the same blu-ray. Deep Space Nine and Voyager are never gonna happen. DVD only.
I am totally fine for TOS to not have a 4K remaster. There’s a point where it’s deminishing returns. How many more toupee lines, ear seams, woodgrain paint overs and frayed threads do we need to spot as the original effects composites just break down even more?
What would be great is a blu ray rescan with no DNR and the glitches and sound mix fixed. If if they want to go ahead and redo the CGI so it’s better and looks more matchy matchy to the era, I would be okay with it. It might even drive more sales among newer fans.
DS9 and Voyager may work if they go back to the films for the live action and do decent upscales for the effects shots. Some shows, like SeaQuest, look surprisingly good. And it would look a damned sight better than the DVD prints do now. But holding ones breath is not advised.