Kate Brown said Richardson wouldn't run for Governor in 2018, but who knows if he changes his mind. He won because he was running against a bad candidate who was viewed as being too ambitious and just wanted to use the position of SOS as a springboard to a higher position.
I doubt Richardson will run for governor, because if he does after only 2 years of being in the SoS position, he'd look overly ambitious himself.
What about challenging Merkley in 2020?
He'd get killed and might not even crack 40%, tbh.