I say the breakup of the GOP was the foreseeable result of the strategy, but not that the strategy was conscious or deliberate in all cases. Certainly, many Democrats wouldn't want to admit they've lost their progressive principles. They'd argue their compromises are good for the country, that incrementalism is the lesser of two evils, and so on.
And as I say at the end, breaking up the GOP could bring on a worse "conservative" party, just as the downfall of Fox News could cause the viewers to be further radicalized as they move on to a more extreme TV network.
The point is I'm not arguing the "strategy" is wise.
But I don't see how a leftist party could replace the current GOP/Trump party. Those rural voters with no college education would sooner move to Saudi Arabia than vote for a Democrat let alone for a socialist party.
Indeed, though, centrists are stuck having to fight against both extremes, that is, against more principled stances on the left and the right. "Centrist" politics in the US is just a cynical business, which is why it was funny when they had to speak of Trump as "transactional" and bereft of an ideology. They were looking at a caricature of themselves in that respect.