If Republicans won 90% of white men (using 2012 numbers for this since I'm using the 538 site), Democrats would need to hold steady with non-whites and win 65% of white women to win.
It's definitely more likely for Dems to win 65% of white women than the GOP to win 90% of white men.
Even if we assume that most whites vote as blocs, there are sizable chunks of white males who tend to favor democrats and probably will continue to (immigrants, jewish voters, super educated, gays, one issue voters like environmentalists, etc.). I'd imagine that Jews + Gays alone = more than 10% of white males.
