I'm reasonably confident that BOI will eventually become a crew base. Resistance from the pilot group would probably be the only reason it wouldn't. A BOI base would significantly dilute the SLC base, and the company will certainly listen to those voices. Senior dudes will not want their seniority damaged by moving flying to BOI.
When? Maybe need more 175s on property.
BOI will be pretty senior...already a lot of folks live there, it's cheap, great lifestyle location, and without some of the odd cultural vibes found in SLC.