I'd like to see an MFA-version of Kerberos/kinit, and a PAM module that checks for ticket revocation on login.
That's not so different from BeyondCorp and Uber's model.
Alternatively, some kind of OpenID Connect init (oidcinit) to get a JWT and then a PAM module like the kerberos one (which also checks the JWT's Key Id for revocation on authentication)