Having a big dongle sticking out of your iPhones lighning port is completely impractical, compared to using the integrated TPM backed storage, unlocked by face-id. Yes there are smaller dongles but only for usb-c and i still don't want to fiddle with it when charging.
It's only a matter of time before desktops gain the same secure key storage as our phones do, add a hardware key to prove physical presence and then yubikeys are obsolete. The only future for yubikeys is for temporary transfer of keys under wrap between devices, where you don't want to use a cloud service for doing so.
While an open api with replaceable internals is a nice idea and one that enabled yubikeys in the first place, once this is integrated in the SoC and the OS, there will be little need for alternative storage backends. What's more pressing now is pluggable synchronization of secrets, for those who don't want their choice of cloud provider to be bound to their choice of OS, or for those who rather synchronize entirely offline through a yubikey.
It's only a matter of time before desktops gain the same secure key storage as our phones do, add a hardware key to prove physical presence and then yubikeys are obsolete. The only future for yubikeys is for temporary transfer of keys under wrap between devices, where you don't want to use a cloud service for doing so.
While an open api with replaceable internals is a nice idea and one that enabled yubikeys in the first place, once this is integrated in the SoC and the OS, there will be little need for alternative storage backends. What's more pressing now is pluggable synchronization of secrets, for those who don't want their choice of cloud provider to be bound to their choice of OS, or for those who rather synchronize entirely offline through a yubikey.