TL;DR: Democrats are united against Trump and will continue to be that way, but if Trump loses so overwhelmingly that he stops running, then a Harris administration will be stuck with a largely Republican government that will keep it from getting much done, thus making it easier for a new brand of Republicans to emerge in two years for for the mid-terms and beyond.
Harris is effectively an emergency nominee, has few policy proposals, scant governing history in Washington and a history of churning through staff. Oh, and she would be the first Democrat to enter the presidency since 1884 without majorities in both chambers, should Republicans flip the Senate.
That adds up to a recipe for gridlock — and perhaps some deal-making to fund the government and avoid across-the-board tax hikes — but not a Scandinavian social welfare state.
The day after Trump leaves the scene, Democrats will lose their best force for unity, fundraising and enthusiasm. But they’ll have the same challenges they do today with the Electoral College, the Senate and the House and the distribution of voters therein.
This is a very roundabout way of saying that Harris is the Hail Mary to avoid another Trump term, but ultimately not actually going to move the needle on progressive policies, and that Republicans are still going to be around in 4 years. We all know this already.
This is the inevitable outcome of centrist Democrats; holding us in place until a “better” Republican can drag us to the Right.
I basically agree with you, but I took it as both a warning to Democrats to stay vigilant and as permission for Republicans to abandon Trump.