I wonder if there will be a big enough market for a very compact smartphone equivalent device that can be used just for credentials? A device that is offline on standby except when you need it. Perhaps the size of a car key.
....wow, that would be reinventing the existing model of the leading ID cards....
Crazy if you think about it :)
As a separate device, it should be offline always IMO, and perhaps the size of a passkey. Or one of those banking devices with a display that show an authenticated text saying what you are confirming.