If Ronnie really won't be there, then my guess is that Dr. Stein may be part of the team in more of a scientific genius support role rather than a hero.
Sure, that's easy enough to predict, but I'm not wondering
what they'll do with Stein so much as
why they've apparently chosen to separate him out rather than keeping him as part of Firestorm. Did Robbie Amell have another commitment? Did the producers or the network decide he wasn't working in the role? Or did they just feel that Garber was too awesome an actor to relegate to a disembodied voice most of the time?