SSH does not rely on SSL/TLS (see RFC 4253). OpenSSH relies on the OpenSSL library, but that's just because it reuses some of the cryptographic functions, which are common to the two protocols (OpenSSL does far more than SSL/TLS).
Therefore, you wouldn't be able to use TLS-OBS as such with SSH.
Would you want to generate a new key-pair every time you log on to a new SSH server, in a similar way to what's suggested in TLS-OBS? Possibly, but you wouldn't necessarily need a new extension to achieve the same goal. You might as well use the current methods: generate an SSH key-pair and add the public key to the authorized keys in your account the first time you log on.