If Marriage Equality gets overturned what do we do?

To be honest this is the scariest thought on my mind right now. Marriage equality was a big pushing point for me accepting my sexuality and all, and the thought of losing it being possible is terrifying. I know people want to play the "oh it will NEVER happen" card but we can't sit here and pretend like its not a possibility. Underestimating those who oppose our rights is foolish in my own opinion. So lets say we wake up one day a year from now and suddenly marriage equality has been overturned, what do we do? I mean my first thought is literally dropping everything else in my life and heading to Washington with as many people as I can gather to protest. I don't know how effective that would be but darn it I wouldn't want to sit there as our rights are taken away all over again. Realistically what could we really do? Do we have to go through another 5 decades of bullshit all over again?