So long as elections remain free, unions have the potential to be a catalyst for serious political change. Here's how it works:
Unions organize enough that they can successfully run their own politicians for office, starting at the city and county levels. (Also, guys, start running for city and county offices. From there, move up to state positions.) Once union-backed candidates start winning seats, we're in real competition with the oligarchs.
Oligarchs control politicians by making campaign donations. That money funds advertising that gets people elected. Unions already have an infrastructure for disseminating information. Large, well-organized unions can sway thousands of votes with a text message. Churches do this all the time. (If you're religious and pro-labor, consider going to seminary, getting ordained, and taking over a local church. The Bible is crazy left-wing when it comes to economic policy.)
Large enough unions become the king-makers. It's no coincidence that Republican-supported voter fraud has risen in step with pro-union sentiment. The GOP is trying to install a single-party system and getting them out of office is our best hope of preventing that.
Also, consider getting a job in law enforcement. Tired of racist, pro-oligarch cops? Become a cop that is neither.