Every election before?
How short is that historical memory, post Carter? Then there are the times we sort of came together and still lost. Dukakis, for example. Is Hillary more liked or popular by the numbers than Dukakis?(though Dukakis becoming known was a weak and engineered by the GOP affair.)
Actual fracturing is nowhere close in either party as it was by Teddy Roosevelt and the GOP progressives against Taft and the establishment, not in your wildest imagination. Nor after all the hullabaloo that it cost Taft the election on its own.
As for JFK's speech on trajectories of the two parties, well ours should have annihilated the GOP decades ago but we bent away from JFK's vision to a Southern Democrat refried pre-FDR dream that has lost its bearings. For decades we have been trying to find a Southern center, conservative, money rich center. The trajectory is bent but we might win in spite of it. As in the dumping of the progressives last century a large chunk of that electorate is powerless in the middle awaiting a new FDR wherever he might come from, whatever crisis might tragically pave the way, whatever right wing coup might arise instead. All those things happened too.