If Dem party internal polls show that Hillary isn’t 100% certain to beat Trump then she won’t run. Even she doesn’t want to be a THREE time loser!
She is running, and she will run no matter what. If the polls say she will lose, she will make the polls say otherwise or else.
This is a scorpion-on-the-frog situation. Will to power is Her essential nature. She cannot sit aside and retire in peace, it is not who she is.