They can only release it, though, if CBS/Paramount provides them with HD prints of the entire series. To my knowledge, they haven't restored the entire run. And it needs some work.
To my knowledge, Via Vision doesn't do HD restoration, they are a distribution label. If CBS/Paramount makes HD prints and provides them, they could do it. They are also incredibly expensive, so that would impact US sales.
Does anyone remember what production logo was used at the end of The Invaders during it's network run? CBS owns it now, but it wasn't a "Paramount" show in 1966-67, right?
They probably worked with what they had. Even Star Trek's current Blu Rays are sourced from a variety of masters. If you know where to look, you can see the color and detail shifts. They did a great job for the most part, but the seams do show. Okay fine, I'll ruin one episode: The Omega Glory...
Other than a couple of first season episodes, they look just fine. CBS was generally pretty good at their releases, but some need restoration. There may not be adequate source materials at this point.
Maybe of there's a movie version or some kind of revival. Until then, I don't see it happening anytime soon. Heck, we're lucky CBS Video put it out themselves and didn't farm it out to VEI. But unless they do a restoration (some episodes look a little crummy and the sound on a few is godawful)...