Remastered TNG is going to sell bucketloads on any format. I didn't get TOS-R; I never completely got into 60's Trek, but I would buy TNG Bluray in a heartbeat.
I'm hoping that if it does happen, we'll eventually get HD upscales of DS9 and Voyager, not complete remastering because they probably don't need it.
I think Voyager and DS9 would require the same level of time and work as TNG, because I think the editing and FX were pretty much done the same way despite the better quality, and I know many if not all of the CG shots are pretty much lost and would need to be redone from scratch (for the later seasons that used CG).
So since they are all 7 seasons, I'd say they're just as much trouble as TNG to remaster in that way, and neither one is as popular as TNG. It just depends on how long it takes before CBS believes it's worth the investment. And let's see how long it takes them to finish up remastering 7 seasons of TNG. I can't imagine them putting that time into Voyager especially (as much as I love it).