This already exists in Chicago at least - just using Android Pay though. I know they also have been working on an app as well, but I haven't paid attention to it once they got initial NFC payments working. I do know transfers do not work with android pay (I imagine due to rotating card numbers), but luckily I don't have to deal with that and Yet Another Silly App.
I will say it's quite great. The time is very near where you can leave your home with only your cell phone as the single item you need to remember. Also scary in that if you lose that single item, you are getting increasingly more screwed. That is now my transit pass, money, taxi ride, and front door key.
Reading NFC transit passes doesn't sound too exciting. I mean, if a phone has an NFC chip, why not use the phone (plus an app) instead of a transit pass, tapping with your phone where you're expected to tap with your pass? This is like your phone wouldn't come with a music player, but would come with a full-fledged oscillograph instead.
That said Chicago seems to have the most convenient system along the lines of what you're talking about -- you can use plain old tap and pay at the terminal with Apple Pay or Android Pay.
Reading balance is not too exciting, as I said. There doesn't seem to be any Android apps to let your phone function as a transit pass.
I understand why it would be cool to let your phone replace your transit pass (as it's cool to let your phone replace your credit card), but I don't understand why it's cool to let your phone replace a transit pass reader.
Replace transit passes and employee/residence/parking garage badges.
Interesting story: I was in London and had an Oyster card but forgot I had the Clipper card for the SF Bay Area too. On seemingly reading the Clipper card, the Tube gate turned orange and basically shutdown.
Thanks for the reply. That does sound interesting and would certainly save a lot of disposable cards/tickets. Here's hoping more interesting uses come about with this increase in user base!
That's something where you are tapping on/off multiple times a day.