when the contract expires, everything in the contract is null & void, including the "no strike clause".

No strike clauses are meant to preclude wildcat strikes, work slowdowns, stoppages, etc... while the contract is in force.

It's been my experience that people live paycheck to paycheck everywhere no matter how much they make, loss of income is not going to scare the majority of the folks out of striking.
Regards
Bill R-4581