Terminology point of order: All "remaster" means is to make a new master tape/disc/file/etc from which subsequent copies can be made for wider distribution. That's ALL. A "remastering" can involve no changes at all - it can just mean to rescan a film reel (and in some low-end remasterings, that is indeed all it means). Casting up stuff like Lucas and his constant reediting of the Star Wars movies is a separate issue.
On a "proper" DS9 remastering - i.e., one taken with the aim of improving the picture quality... as has been said, it's highly unlikely to happen in the way of TOS-R because of the cost: unlike TOS-R, where they had full and final edits on film, they would need to redo all the post-production work from scratch (including all optical effects, such as phaser blasts - although, contrary to popular belief, only the CGI visual effects would need to be completely
redone. They could recomposite any model shots where they still have all the elements, with only stuff like phasers/photons/etc actually needing to be redone from scratch).
So it's a moot point, really. They aren't even likely to do a TNG-R before the day they can't sell the SD version at all.