I think it's premature to call for a potential 2020 candidate right now without knowing the circumstances of the times.
As far as Kander goes, him, John Bel Edwards and the Montana govs are the kinds of dems that can make inroads in more rural areas. As far as what needs to be sacrificed nationally, I think gun control - or at least the language for it - needs to be sacrificed to the altar in order to flip at least a certain percentage of those voters for presidential elections.
Now that I think about it, the dems have never been the same since they lost the politically savvy southerners of the party.