Came across this post re Horizon Air on another forum. It's dated 22Jan18:
"For anyone who was interested in Horizon's RTP (said to be announced "in the coming weeks" back in July, then said to be final in January) here is the latest update.
"Thank you for your email and interest in Horizon Air. We are still in the process of creating a Rotor to Wing program. We do not have an ETA on completion at this time. Please let us know if you would like to be added to the list of people that would like to be contacted once we are ready to launch the program."
Just passing the word along"