I would actually like to see B5 remastered, but I don't think there's big enough of a following for WB to do it.
Not to mention that the original VFX files/models have been lost.
The best you're ever likely to get would be a remaster of the existing (does it still exist?) live action footage, with upscaled VFX, much in the same way that Firefly on BD was handled. There is an additional problem though - the composite shots were rendered at 720 x 480 pixels (for 4:3) - That gives you problems if you try and change the aspect ratio like they did on the DVDs (16:9) as there's no way of doing that without impairing the video quality.
Hence, the only way the series could be remastered, without going back and doing the composite VFX and re-rendering them, would be to retain the 4:3 aspect ratio (like the TNG BDs), and upscale the VFX and composite shots.
But then you're back to your point WBs would never do it because they don't seem to think that there's enough people to worry much about B5 anymore.