Mobility-as-a-Service will only work if cities can evaluate markets of multiple operators, and consider not just ridership but also the incentives for transferring costs (fares, access/egress, wait time, in-vehicle time) between operators and travelers. Saeid Rasulkhani and Dr. Chow just published a new modeling framework that explicitly considers these trade-offs, developed with funding from NSF (CMMI-1634973). 

Link to paper: dx.doi.org/10.1016/j.trb.2019.04.008