The goal of all the capitalist inititiatives-- the detention of immigrants, the extension of the workweek, the privatizations-- is to reduce the cost of labor and transfer wealth from labor to capital. If immigrants are terrorized to the point that they feel they must take work at any wages, wages of all are driven down. If the work week is longer, and thus there are fewer jobs and more unemployed, wages are driven down. If work is transferred from a higher-wage public workforce to a lower-wage private work force, wages are driven down.
Total working class income is already below the level, in most countires, needed for the reproduction of the working class at its existing standard of living, as witness the very low birthrates. The EU initiatives, at a time capitalism is entering a cyclical, and probably severe, crisis will greatly increase the gap between actual working class pay and the real cost of reproducing labor.
As Luxemburgist and others on this forum have argued, we need to reply to this not with a disjointed series of protests against individual directives, but with a single, coordinated campaign that not only opposes the directives with a single policy, and poses a real working class alternative. This is a vision of what we are positively proposing to make things better, not just to prevent them from getting worse.
In the context of a movement for such broad demands, strikes, which can develop a mass character, spreading beyond individual employers or even industries, can win concessions. Without such a movement, they will, in this period, mainly lose.
There was a small, but concrete example of this last year in Chicago, where a strike by non-unionized workers, mainly immigrants, was won only because the immigrant rights movement was able to mobilize to the strikers aid, and call upon African-American community groups to prevent African-American workers from replacing the strikers. The strike was purely defensive, and resulted only in the re-instatement of fired workers, but in a period where strikes by unionized workers in the US almost invariably lose, it shows what could be done with a broader movement. In this case, capitalist efforts to pit immigrant against native-born workers were defeated.