It seems more likely to me because our first-past-the-post elections make a two-party system a mathematical certainty. If one of the major parties implodes, something else must take its place, and a faction among the other major party is much better equipped to attract the newly unaligned voters than third-party also-rans.

Manchin and the DINOs will go one way, AOC and The Squad go another. Party leadership will align with the former over the latter, so the Democrats become the new right-wing party. Whether the left-wing faction joins with the Green Party or the Greens become a faction of the new left party is a distinction without much difference.