I was half joking about Dazzler but continuing with the X-Men mutant rollout methodology, introduce Dazzler in a cameo appearance. Gauge fan reaction, then see if it warrants a solo movie or larger role.
That's how they introduced Colossus, Cable, Kitty Pryde, etc.
The upcoming Phoenix movie maybe a great opportunity to squeeze Dazzler in there.
Disney now options all actors to 6 picture deals to lock them in for 2 trilogies. They need younger actors and actresses.
Once you get the movie cameo, the 2 aforementioned Dazzler books will spike. If a solo movie kicks in, it has the potential to be a key.