A company cannot decertify a union -- it is illegal. They can, however, try to "break" the union. However, the employees can attempt to decertify, but there must be no company management at any level with their fingers in the mix.
A company can hire permanent replacement workers (thank President Reagan for taking the "teeth" out of a strike)at any time during a strike. When the strike is over, the strikers are put on a waiting list for the first available vacancies by order of seniority. It is illegal to terminate permanent replacement workers because the strike is over and the strikers want to come back to work.
If the strikers are "locked out" by the company, they might qualify for unemployment compensation while on strike, as well as some other State programs (free lunches for kids, etc.), depending on the State.
Basically, a strike is the last thing you want to do unless your skills are such that it would be extremely hard to replace you or the job market was very tight. The first thing I would have tried -- if the local was well-off financially and with the concurrance of International -- was to bury them in grievances.