Kristof and Sullivan should stop worrying so much. The bitter rancor that typifies the current left-right divide in the US is a cyclical phenomenon, riding on the confluence of a trio of polarizing factors that will inevitably dissipate:
Of course, these three factors tend to decline with time, as political waves of change peter out, as the intensity of major crises dissipates, and as dominant leaders eventually lose their aura of invincibility and are shunted aside. As Kristof notes, "Europe has matured and become much less polarized" since his time there. There's no reason not to expect a similar outcome here, in due time.