Babylon 5 is never, ever coming to Blu-Ray, certainly not in HD. A company that actually cared about the program and had serious piles of cash to invest into it would have to assume the rights, and Warner Bros. hasn't shown any interest in the past in selling it.
Plus there'd be a massive amount of restoration needed (the FX would have to be done from scratch), just like with TNG, DS9 and Voyager. I'm not sure any company's going to pony up for something like that. It would also take too long...