What’s sad is how many people will only remember him as Flounder. Vir was so much more of a stretch for him as an actor. (Who killed the mad Centauri Emperor? It wasn’t Londo.)
I know he’d been battling health issues since Babylon 5 was still in production – at one point he minimized his appearances for a while and came back to the show much thinner. Despite that, I guess those problems still caught up with him.