While no current air threat exists, IMO that can easily change and quite rapidly.
With Russia devoting more resources to northern facilities, I can foresee more incursions by Russian aircraft into northern Canadian waters. Especially if the Northwest Passage starts to become open for longer periods of time as the climate changes.
While those incursions would fall under NORAD's area of responsibility, USAF interceptors are not, IMO adequately positioned to handle polar incursions of Canadian airspace. Nor should they be, given that Canada is also responsible for contributing to the defence of North America.
What concerns me though, is they while new threats and potential threats are emerging, the steps which need to be made now in order to have a better positional response to emergent future threats, appear to be getting discarded because there is not a need, "right now..." Meanwhile, the fact that it now can take several years to develop skills and capabilities to properly respond appears to be getting completely ignored.