Since the market for cast albums skews older, I think they will be around for at least a little while, but the reckoning for CDs may be coming. Most new cars and computers don't have CD players anymore, and stores like Costco or Target have an extremely limited selection. Younger people aren't buying them. Many rap albums are released on digital only, or with the CD version released months later.
Interestingly, vinyl is making a big comeback. Something like 15% of physical product sold in the US is vinyl rather than CD. And vinyl is typically sold at a premium compared to CDs, which record companies like.