Use the intervening years to vote in local politics, primaries, whatever else you have. Take action, don’t just wait for the next presidential election to make a vacuous point of non-participation. Boycotting votes does no good, and in a top-heavy system, handing over control of the top to the still objectively worse side is too much of a gamble, but building progressive support from the ground up is not just safer, it may also make the bend-overs worry about their own dominance enough to start at least holding the rope and make life a little harder for the other side.

Also, support whatever measures you find to abolish FPTP. It’s the reason the whole thing is a tug of war in the first place. Just about any alternative is better.