CYKA, Prince Rupert and Terrace aren't exactly ghost towns. Prince Rupert has about 17,000 people, while Terrace has a population of about 20,000. Kitimat (I'm not even sure if it even has an airport, but it's not that far from Terrace anyway) has about 12,000. This amounts to at least 49,000 people in the North Coast region - only a bit bigger than Fort McMurray. Prince George has about 77,000 people, so there's more than enough demand for WJ flights.
Because of a lack of a viable highway to Vancouver due to the Coast Mountains and the rugged terrain of BC's coast (although there is a marine highway system, traveling times by ferry must be pretty slow compared to going on a regular highway), demand for flights in the Prince Rupert/Terrace/Kitimat area has been historically high, I think. After all, CP used to fly 737s into these airports and AirBC until recently was using BAe 146's on the YPR/YXT-YVR route.
IMHO, WestJet may start flying into Kamloops or Prince Rupert next in Western Canada. In the east, Montreal at St. Hubert is likely to be next, although I'm not sure how soon.