Say you run a company in an industry with unionized labor that could strike for several weeks or longer; what would you do about that possibility? You can do two things:
Unless you expect replacement labor to cost more (inefficiency and newbie reputation damage, like the '87 NFL season) than suffering through the expected strike time length, you should extend your talent farming tactics to line up prospects well in advance of when they sign contracts. You should also insure against the risk of a strike lasting longer than N days (where N demarcates the maximum strike length you can withstand).
Unions should work to emphasize the inferiority of replacement labor, and try to poison the farming of new talent by unionizing them as early as possible (free/reduced-cost membership while full-time in accredited school?). Unions can do nothing about the purchasing of insurance.
This predicts a vibrant market in strike insurance. The US railroad industry created an internal insurance program, and so did the US airline industry, however the airline industry's failed. We see companies doing Contingent Strike Risk insurance, where you get money when major suppliers/customers halt due to strike.
We see no direct strike insurance market. Given the adverse selection and moral hazard issues, insurance companies should write strong contracts that specify the rate increases and automatic contract renewal that occur when a strike occurs. Employers should purchase the insurance and then work to prevent strikes to avoid the automatic increases in insurance cost. Granted, as soon as the terms of the insurance contract become known to labor, they can threaten to strike and greenmail from the employer some percentage less than 100% of the penalty increase. Perhaps that's why strike insurance doesn't work?