Ok, my guesses:
Still steel wheel on rail, heck, you could even (concieveably) run a lowV on it.
Third rail voltage "bumped" up to maybe as high as 1kv. Still DC.
Cars would use (by this time) inexpensive, single piece, unibody, carbon fiber bodies, riding on aluminum alloy trucks, possibly even axles and wheels. suspension would be combination airbag and active computer controlled dampers, making a ride so smooth you can balance coins on handrails.
Trucks would be radial. Motors would be 3 phase induction AC types with built in inverters and regenerative braking to 0mph. Hydrualic actuated disc brakes would be used as a backup and for emergency braking. Traction circuitry would be confined to the truck, with only a lead for feeding the static inverter and battery pack under the car, and a feed for braking resistances. All truck / train communications would be via a single 6 lead cable. Failed traction gear would be replaced in shop as a whole truck/motor unit, though reliability would be so great that such a procedure would be rare.
Control would be semiautomated, possibly OPTO. Inteligent doors and an automated control system would assist the T/O in normal and emergency operations, and communicate with token booths (now expanded more into service centers at stations where they still exist) to help predict passenger loads, and route fire/police personel in an emergency. Cars could sense the passenger loads, and automated voices in stations would guide passengers to empty cars.
Signalling would be a form of CBTC, with no trip arms. Trains would run in semi auto mode, with the T/O making acelerate/decellerate/speed decisions, while the computer monitors for safety and timetable performance. An earpiece (assigned to each T/O - coul you imagine sharing them? Ewwwww) plugs in to the console to give access to the controls, and communications. It monitors the T/O's pulse and temperature to serve as a deadman. If the T/O is incapacitated, the train automatically notifies the command center, the signal system clears a priority path to the next available station, and stops there.
Fare access would be via a small wand type farepass. This could be purchased or refilled virtually anywhere, and would also provide fares for commuter and high speed lines in the area
Maintenance work would still be hands on, but small, automated, "rover" type rail cars would work the system at night, looking for defects, and possibly even making small repairs. A larger automated car (controlled by an operator), would stop at stations, unload a cleaning machine that would clean the floors, and come back at a later time to pick it up.
Here's the scary part. Just about everything I've listed here is either technically feasable now, or will be in 10 years.