Oh, god I hope not. It would cease to be America. We are a constitutional republic. Everything about socialism and a social democracy disagree with the founding principles of the US.
Not now, it could happen sometime way way down the road, but if it does, I have a feeling there might be another historic civil war or something like that. Unless there are a solid majority of Americans that want a social democracy then there will be a fight.
Because it's not like France is a constitutional republic founded upon the principles of freedom or anything.