I find it more likely that that a break in the democratic party occurs, between center-left (Warren/AOC/Sanders et al) and the center-right (Clinton/Biden/etc). The right of center democrats would more likely absorb all the now-homeless Republicans like Kasich and Romney than any new party. I get the impression that the real elections will be democratic primaries for the next few cycles, with the November elections just being formalities.

The fringe Trumpists will continue to have their party, at least for another few election cycles, until they've finally been thoroughly wiped out of the electoral digestive system.