Using the F-35 in the defence of Canada/North America role is mis-use of a valuable asset. You don't need stealth and all the sensor fusion to go after drug smugglers/terrorist hi-jacked aircraft or the worst case scenario TU-95 Bear-Hs coming over the North Pole.
You can accomplish the same mission with aircraft like the
KAI FA-50 or
Leonardo's M-346FA.
Or go with the South Korean
KF-21. The first basic version of the KF-21 is planned on entering service next year and plans are to field upgraded versions resulting a full stealth version by the 2030s. Much more likely to the KF-21 stealth version in service before the GCAP/FCAS.