Rewire would dramatically improve the usefulness of Real Band for me.
What I would be looking for is a way to use RB as a plug-in (Rewire or VSTi - I don't care which) in Cubase or Samplitude.
I have a lot of good-sounding soft synths, but they either crash RB/BIAB or if they do work, I can only use one at a time.
But there really isn't anything that matches the "real" factor of Real Tracks, so I usually do the Real Tracks and export the audio.
The drawback is I have to redo the song to change key or tempo.
I don't really want to pay for the power of Cubase or Samplitude built into RB/BIAB,
But being able to link RB/BIAB to my DAW via Rewire would be a big step forward.