For me the key quote from the release is the last sentence:
This interline agreement is the first phase of co-operation between the airlines. WestJet and SAS intend to expand the partnership to codeshare in the coming months.
With DE, VS and [hopefully] soon SK, WS is slowly building a more robust network of direct WS-coded Canada-Europe flights beyond YYC. I assume this agreement will also mean that SK moves from T1 (the infield terminal in reality) to T3 at YYZ sooner or later...