Three factors:
1. The minority vote increases a bit every 4 years. I have trouble believing that the minorities who turned out for Obama will stay home for Hillary, and even if a few do, won't the fact that country will be a bit less white balance that out? Regardless, the Hillary turnout operation should be just as successful as Obama's.
2. The minority vote should be at least as Democratic in 2016 as it was in 2012. Will Hillary do any worse among minorities than Obama did? I doubt it.
3. The white vote should be at least as Democratic in 2016 as it was in 2012. I have a lot of trouble seeing Hillary doing worse among white voters than Obama did.
If all three of these factors are true, and Hillary runs, I can't see a path to victory for Republicans. Agree/disagree?