The same poll you are citing shows that Hillary's favorability rating is at its lowest point since June of 2008, and her unfavorability rating is at its highest point since June of 2008. (That's using CNN-sponsored polling's OWN past numbers - it's not comparing X to Y.)
So what? It's nearly the same as her favorables in May 2014. Regardless, even Hillary's numbers in June 08 are far superior to any of the Republican candidates.
In Obama's comfortable 2012 victory, he lost the white vote 59-39. So a 43-54 favorable rating among whites is pretty damn good. And you're overestimating how far minority turnout will fall. Blacks still turned out for Gore and Kerry after all. If Hillary wins 40% of the white vote, she wins the election.
