It is very unlikely that TNG, DS9, or VOY will ever be remastered for release on Blu-Ray. If I recall correctly it has something to do with the film they were recorded on that will make it very grainy on a Blu-Ray player; plus it is very expensive to redo all of the visual effects to support the new format.
I disagree. The quality of film is not a problem, as even 8mm film can be scanned at high resolution and look great.
The trouble here is how the effects were done. If they were composited on video tape like TNG was, they'll have to redo them. It's hard to believe that later DS9 and especially Voyager would stick with the archaic video tape composition method, especially with CGI coming into play.
Either way, the fanbase for these shows is off the charts. Star Trek is an enormous cash cow for CBS, they just need to realize it.
I can't see redoing effects shots in CGI being too terribly hard, most likely it would just be costly. They have to have a lot of CGI stuff on file so making new shots shouldn't be too hard right? DS9 in HD would be awesome, the space battles could have some more variety perhaps. Of course, it's just wishful thinking.
That post that was linked to was an interesting read. B5 would be awesome to have in HD as well but the costs of redoing all of those effects would probably not make it worth it.