The original Babylon 5 and EAS Cortez CG models re-rendered to modern HD standards (with a new background). Whilst the Warner Brothers film masters wouldn't look this good, they'd be big improvement over the DVD versions of the show.
The only way to get a HD Babylon 5 would be to go back to the original film stock and extract a new HD image of all the live-action footage - which is time-consuming and tedious, but straightforward - and then re-render all of the thousands of CG effects and composite shots* in the show from scratch - which would be mind-bogglingly time-consuming and expensive. Star Trek: The Next Generation took this approach, but the show didn't have much CGI to re-render, as most of the effects were handled in-camera on film, so it was straightforward to remaster. It still took four years and cost $20 million, and took years to break even across multiple media releases and years of streaming on Netflix and CBS All Access. Babylon 5 would cost around twice that as it had far more CG than ST:TNG and in fact far more effects shots in total, despite being almost seventy episodes shorter in length. Given the relative obscurity of Babylon 5 compared to ST:TNG, this would appear to be commercially unviable.
(* a composite shot is one that combines live-action footage with effects, so any shot which has weapons being fired, the characters standing in front of a green or blue screen, interacting with CG characters etc)
However, Straczynski has completely upended this understanding of the situation with new information.
It turns out that at the end of every season of Babylon 5, Warner Brothers requested that every episode be completely re-mastered on 35mm film. This was for an archival copy to sit in the WB archives and to match the show as broadcast. This process involved taking the digital elements - including the original CG shots in their original resolution (noticeably higher than what we saw on TV from the video master) - and putting them on film.
So in order to get a full HD version of Babylon 5, all one has to do is extract a broadcast copy from each film reel, and since everything is on there already - including CG - that's all you need to do. It's extremely cheap.
This may sound too good to be true, and there is a hitch. Because this was an archival copy of the episode as already aired, it only involved the 4:3 TV format, not the widescreen master which only exists on video. Or to put it another way, Babylon 5's HD edition would only be available in 4:3, not widescreen, despite Babylon 5 being the first TV show ever filmed directly in widescreen. Which is both ironic and immensely frustrating. As long-term B5 fans know, the CGI for Babylon 5 only exists in 4:3, with the widescreen CG shots seen on the DVD release coming about from cropping the image (which is incredibly annoying, and loses information from the top and bottom of the image), so this would both restore the original CG image and in a much higher resolution, but at the cost of losing the live-action widescreen shots.
There is the possibility of going back to the original film stock for the live-action-only shots and combining those with this new master to get at least some of the show in widescreen HD at a still-reasonable price, but the series would need to switch to 4:3 for every CGI and composite scene, which would be rather distracting.
Whilst it's not a perfect solution, it does open up the possibility of seeing Babylon 5 in high definition, at level of visual quality never seen before. Whether Warner Brothers are prepared to invest such a remaster remains to be seen, but at least now, in the long, twilight struggle of rewatching your favourite twenty-year-old SF show, there is the possibility of hope.