i mean that's a subjective thing. in terms of polarization, i think both parties have moved from the center (pubs first, but dems seem to be intent on catching up - the 2020 dem candidate is almost certain to campaign way left of 2000, 2004, 2008 candidates). but i'd say the most dramatic change has been the pub shift to nationalism. racial/ethnic correlation with party identity has also increased, and seems to me likely to continue increasing - which likely has and will continue to influence policy divergence.