The 321s were never slated for retirement. They'll be around especially with the purchase of the NX (expect more orders imo).
They operate 2 versions of the 320; the -211 and -214. The -214s aren't getting retired anytime soon since they're 100% part commonality with the 321 (engines being the main thing). The -211s are a surprise to see come back from storage (for Jetz mainly).

As for the CRJ, they haven't been updated other than the addition of seats in the original -705s. Tails 717-721 have their original interiors and 722-730 are pretty much new. No plans as of yet for a new interior.
Same can be said for the Embraers. Express has the issue of staffing which prevents a long term fleet plan as of now,