Comment by lxgr

They'll probably keep it around either indefinitely, or will replace it with a fully account-based scheme where there's nothing stored on the card itself (i.e. no stored-value balance) other than an authentication key for the card number.

That's the model they already use for bank (credit and debit) cards too, so they need the backend to manage a deferred account-based system anyway. That's also what the MTA in New York does: They've never supported stored-value cards, and their new physical OMNY cards are effectively just a weird type of closed-loop EMV payment card.