A common client user file is needed as transit morphs to intermodal multi-provider linked trips. Depending on the destination and need, one might use bikeshare, carshare, microtransit, public transit, scooters perhaps, and robocars. One client user file is needed with the basic information: Name, Address, Contact Info, Payment Info, and Accessibility Needs (if any). A common data specification is needed for this information that is mode-agnostic, to be communicated to any participating ride provider - transit system, microtransit, taxi, or automated vehicle network enterprise (AVNE, anyone?).
By the way, other common data fields would pertain to the trip origin and destination, number of riders (companions, personal care attendants), & latest arrival/earliest departure times.