I'm struggling to follow how a union could help this situation. What would happen? Workers would go on strike if their firms use robots? Seems like that would just push the owner to accelerate robot orders. My guess is that unions are pretty useless in the face of automation. Does anyone know any precedents?

I agree in spirit though. What I think is likely is the rise of populism. I think the battle will have to be waged in the political arena.