Well, this has me interested, maybe even intrigued, but not necessarily excited. For all its numerous and obvious failings, the original got so much right that a remake by the same guy seems kinda ... bold. Especially given that there's no guarantee that there won't be a repeat on some of the critical issues of the original (uncertainty if there'll be the chance to complete the story arcs, budget constraints, developments in cast and crew necessitating improvisation).
At the same time, JMS's reasoning for doing this seems sound, and as someone that's created something over the course of years (not a creative work, as an academic) and that has to live with all the shortcomings baked into it due to my own inexperience back in the day, I certainly see the appeal of trying to do it all over again with a few decades extra in experiences.
It doesn't have to be a 5 season narrative.
If he has the leeway, he can spread it out to as many seasons as CW will allow.
JMS is a vocal proponent of the five-part dramatic structure of introduction - rising action - complication - climax - denouement and set out to realize it season by season in B5, with it kinda falling apart in season 4 due to him thinking he had to wrap it all up by the end of the season. There was some drama between him and some and the cast and crew (most notably Jerry Doyle) after season 5 since he didn't try to get the show renewed past that point, seeing as he had finished telling the story. I'm sure he could fit the story into many different molds if necessary, but all things being equal and til he says something to the contrary, my guess is that he would aim for a five-season structure again if feasible. (Who knows if it will be.)
Claudia Christian is Ivanova's mother?
Given the acrimonious nature of her departure and the aftermath, of all the original cast reprisals I'd like to see, this one is way up top on the list. Would be nice to wash out that bitter aftertaste. (As an aside, JMS is explicitly asking people not to post concrete story and even casting ideas & wishes - specifically who should play what role - anywhere, even in jest, since any idea being out there on the interwebs with a time stamp that predates his scripts & postings can complicate matters for him legally if he actually wants to do a thing - so fun as it is to fantasize about these things, we really shouldn't out loud.)
I've already seen people badgering JMS on Twitter to please not make the reboot "woke", and ... boy do these dudes have a rude awakening coming. Because given the plans JMS had with the Minbari but couldn't realize at the time/get away with ... there are going to be some things.