There are a lot of potential consequences. A look at US labor history shows that mass arrests are possible (one of the first uses of aerial bombing was used to

There are a lot of potential consequences. A look at US labor history shows that mass arrests are possible (one of the first uses of aerial bombing was used to put down a miners' strike at Blair Mountain in the US. So, much worse than mass arrests are possible). But, usually the ruling class + capitalist class targeted those they identified as labor leaders (often with bogus charges-- even without evidence, these often ended in convictions. With some of these convictions resulting in the executions of innocent people). But, just firing all workers who participate as was done in the 1980s when air traffic controllers attempted a strike would likely be sufficient to scare the working class back into compliance. Or, for a larger action, you could punish the entire working class by sharply raising interest rates and inducing a recession. With the resulting large supply of unemployed/underemployed workers, labor will be too weak to make demands.