Although interesting I think it is a fad anyway.
Why? Because if you rather carry your credentials in a mobile phone the
phone can connect to the other devices you have and provide local roaming.
What's the point with that you may wonder? Because in the phone
credentials can be secured in an entirely different way than in the Cloud.
In addition, the phone scheme works for all sorts of credentials including
those which you will never be able to replicate/copy such as PIV and EMV.
There are of course pros and cons to all solutions so we can only wait and
see what actually survives out there. It is also a matter of bringing out
useful incarnations of a technology.
Anders
http://webpki.org/papers/keygen2/sks-keygen2-exec-level-presentation.pdf