I'm sure that some already suggested or talked about these ideas before. If so, I apologize.
Here's a couple of ideas (warning: I'm still relatively new to BIAB so I'm not sure these suggestions actually make sense ....)

1. increase the number of tracks in BIAB.
I know that with Real Band you can have an unlimited number of tracks. But maybe I'm not the only one who prefers to work in BIAB rather than Real Band (for a number of reasons, I find it easier to go from BIAB to my DAW rather than using Real band). So, it would be nice to add at least a couple of tracks in BIAB (from the current 7 to 9 or, even better, 10). That would give more flexibility and variety to the arrangement and the styles.

2. Increase the number of "sections" from 2 to 3 (I mean, instead of just A and B, it would be nice to have A, B and C for each track). The advantage, obviously, is to have more variety within a song - indeed, many songs have three different parts in their structure (verse, bridge and chorus). I realize that this would be almost impossible or very difficult for existing realtracks, that's ok, but maybe it could be done for future realtracks? I think this would be especially useful for drums (in fact, many drum tracks already have several variations ... but we can only use 2 in each song ... it would be nice to be able to use more than 2 variations of the same drum track in the song)

Just my two cents. Looking forward to BIAB 2017!!!