CRJ550 Launched to replace 50 seaters.
United is behind the game on Premium Economy seats. This helps them catch up.
AAG has seen huge success domestically on premium economy seats.
If the route is selective to support mainline routes and range (CRJ700) and timed just right at peak travel season, this could be very profitable for United. AAG being a reactionary leadership/company might find this 3-cabin Bombardier configuration the way to expand premium economy on select routes. If demand, scale, and “the ability to compete” justifies it.