It will be very hard for a white Democrat to replicate what Obama did simply because blacks are racist voters - they voted for Obama in exceptionally high numbers out of racial solidarity. That’s why he was able to win the White House twice with a minority of the white vote.
Black turnout won’t be as high in 2016 and Hillary - or any other white Democrat has to face the fact if black turnout is going to decline and the Democratic share of the white vote remains the same - that Democrat is going to lose a national election. And if the Democrats don’t address their white male problem, they’ll be looking back nostalgically on the Obama decade.
The key to 2016 is probably the upper MidWest and states like Colorado out west. If we accept that most likely the dem nominee isn’t going to get the high rate of minorities like Obama did then the key would be white middle class voters