I am not sure how you link O&M to ridership, which fiscally impacts costs to taxpayers (i.e., with more passengers per day, added fare revenues will reduce the amount that needs to be subsidized).  If the trains run on a fixed schedule, full or empty, they still require the same number of personnel involved in operations, and they still need about the same amount of maintenance per day.  If anything, fuller trains might increase O&M costs slightly (due to added wear and tear), but would reduce taxpayer subsidies so more riders means better cost-effectiveness.  A successful conversion to maglev would bode well for both local and federal approval for future extensions that would bring dramatic increases in ridership.