Personally, I have concluded that Trump voters, and only Trump voters, are an absolute dead loss. Could some of them be "won over" to vote Democratic in the next election (assuming the continued existence of free and fair elections)? Oh, absolutely. I definitely know people who voted for Obama and Trump.
But I have to ask, what's more important to me, numbers or values, and my conclusion is that it's values. We've had a Democratic party that tried to be everything to everyone and wound up being nothing to anybody. We can approach this as a statistical problem and gobble up every word Nate Silver has to grace us with, or we can learn to lead.
Anybody who voted for Trump, _particularly_ if they also voted for Obama, _particularly_ if they identify themselves as "not racist", has demonstrated a critical inability to live up to the courage of their convictions. And as long as that situation exists, it is a waste of time for us to try to appeal to them knowing that they'll turn on us for the next asshole with a bullshit slogan.
Now, if we want to teach them to have values, hell yes, that's worth doing. But the only way we can do that is to have values ourselves.