Here we go:
https://www.pressherald.com/2018/04/...e-in-portland/
The service is currently scheduled to end in November, but Tyri Squyres, the airline’s vice president of marketing, said a decision on whether to extend service, and when to resume flying next year, won’t be made until Frontier can gauge interest in the service.
So maybe a partial misunderstanding on my part, there is at least the
option to extend beyond November, and frankly I would be surprised if they didn't take the option on that.