age polarization reversal in 2016?

[memphis]

The Dems do a bit better among young whites than among old whites, but not much. Most of the age polarization comes from old people being much whiter than young people.  Something big is going to have to change for the GOP to have a prayer in 2016. But Republicans will only consider marketing changes and electoral process changes instead of product changes. That says a lot about them.

[memphis]

The Dems do a bit better among young whites than among old whites, but not much.

18-29 generation of whites isn't uber-Dem?

Hardly. The 2012 exit polls had them at 44 Obama-51 Romney. All other age groups of white were about 39 Obama-60 Romney. There's a real difference beyond statistical noise, but it's not that big a difference. 
Link: http://www.foxnews.com/politics/elections/2012-exit-poll
As for why older whites used to be more Democratic, I think remembering the Great Depression and the Democratic response is important. A lot of those folks knew actual hunger. Not so much the case today.