Part of stopping service to K Falls and Coos Bay was the early retirement of the Q200s.... I don't think even falling oil prices are going to change that decision (personally, I'm sorry to see them go - I'm hoping to get on the last Q200 flight from here to Portland).
My anecdotal experience from sitting in Terminal A for a couple hours once or twice a week during the evening "rush" is that the Klamath Falls and Coos Bay flights, even at the peak time of day, weren't all that full.
Dave
Redmond, OR