The Democratic Party hasn't won the white vote since 1964, and they still have sizeable support from younger whites.
Although I believe I read that this support is tapering off generationally. I remember Cuccinelli won white 18-24 year olds but lost white 25-40 year olds. The general argument being that those who became adults when Bush was President vote Democrat and those who became adults under Obama vote Republican.
http://www.newsmax.com/Politics/Cuccinelli-college-women-poll/2013/11/08/id/535605/
Virginia youth do not represent the youth nationally. Virginia is turning blue largely because of the 25-40 crowd moving to NoVA. The young vote in Virginia is situated largely outside of NoVA and acts more like southern trends.