I think the "party switch" narrative is an oversimplification, as it does not represent some sort of overnight change in party platforms, but is rather the result of the disintegration politically of the "Solid South" that previously was essentially a one-party state (outside of Texas and East Tennessee, and possibly Western North Carolina).
Simply put, whatever your political ideology in the South, you were a registered Democrat and voted Democrat and ran Democrat if you wanted to win any political race. By virtue of the populace leaning more politically status-quo (I don't think it makes sense to call them "conservative" in today's sense of a political conservative), those types of candidates won. Change in party-line voting reflects more the change in the composition of Democratic Party candidates.
The election of 48 was perhaps a signal in national elections, but it didn't change anything about local or statewide Democratic Party dominance in the South. I once wrote a paper on the subject.
In the late 1960s, seeing political opportunity, some heretofore status-quo Southern Democrats switched party affiliation. No doubt, Nixon capitalized on this growing trend with appeals to the "law and order" crowd. But again, this isn't some major ideological leap by either political party. As Southern Dem politicians left the party in gradually greater numbers in the next 30 years, it was increasingly a more "social justice" party due to removal of the former candidates. More process of elimination than a conscious "switch."
Did the Republican Party receive an injection of more "social conservatism" as a result? Sure, but I'd argue the Democratic Party changed far more, by virtue of being left without its more old school wing. The Republicans had fiscal conservatives already, and still do. The Democrats didn't so much "switch" as they gradually lost an entire faction of the party candidate pool.
Basically, I'm not saying what you've listed is wrong. Most of it is just factual electoral results. I just think the "party switch" narrative is better understood through gradual political defections by candidates (and eventually, voters), rather than some overnight revolution or a great ideological leap on the part of either party.