That'd allow verifying every single new coin (unless it is damaged to the level of breaking the rfid chip, but I suppose that's not that easy).
It'd also enable tracking. I kinda regret that idea now. BUT if used responsibly, that can significantly reduce the counterfeiting by the means of somehow cloning the RFID chip (which wouldn't be simple if done properly -- there aren't any successful attacks on proper implementations of stuff like mifare desfire EV1/EV2 afaik). A coin was used on a market on london on 10am and with an ATM on Glasgow on 10:30am? Yeah, flag that coin down.