The devil is in the details of the proposed contract. If WestJet pilots got more than what management was willing to offer in their best and final offer, then presumably it was worth it - and it also shows that a threat of a strike was worth it.
WestJet operated 70% of its flights yesterday and was planning to do the same today - so there are either a whole lot of pilots that didn't plan to honor the picket line or the company has a very large number of management pilots that could take over flying duties.
If the pilots really achieved more than the company was offering, there is a very good chance that pilots at one of the remaining US4 airlines - AA, WN and UA - will be emboldened to push even harder. While a separate market, the US and Canada are as alike in many respects as any two economies.
And let's also keep in mind that pilot and flight attendant contracts remain open at AA WN and UA and many other global airlines. Companies know that if they settle w/ pilots, they have to settle w/ FAs too. DL's rich contract for its pilots and its pay raises for FAs plus adding boarding pay significantly escalates the money that the airlines will have to spend - and AA, WN and UA clearly don't want to spend that much money because doing so will wipe out a far higher percentage of their profits than DL which gets a much higher amount of revenue from non-transportation sources including its loyalty program, contract maintenance and its refinery.
AA, WN and UA clearly cannot absorb