Something you might be over looking is that Sanders, although he won't get the nomination, has demonstrated there's political viability to the left of where the Democrats have been. Democrats like Hillary can claim moderation as long as there continues to be a presence from the socialist/liberal wing of the party. The GOP won't really have any viability (in terms of numbers) without the Tea Party base, which is why they went down the fire-and-brimstone path in the first place to counter the changing demographics that favor the Democrats. The GOP, for however much it would like to claim moderation, still don't seem to advocate policies that favor the emerging class of people that will make up the middle--I just don't see them peeling off moderate Democrats, without a shift in policy. As much as we talk about how crazy Cruz and Trump are; Rubio's advocating much of the same, with growing the military, destroying our enemies (ground wars), being tough on immigration, repealing Obamacare, etc.