I found it very interesting, my friend. As I thought about it, though, I'm not surprised. There are two things that account for this, in my view:
First, most of the South is coastal. It is more dynamic (people moving in), physically closer to the Northeast than the Midwest, and more involved in international trade. It has more of a migrant population, too. The urban-rural population divide leans urban (Atlanta, Miami, Nashville, Memphis, etc.) The skew is the rural- urban ratio, and the fulcrum is the suburbs. The more and bigger the suburbs, the weaker the GOP gets (think Virginia and Johnson County Kansas, suburbs of KC, where Sharice Davids won).
Second - and remember, I'm a native Missourian - Midwesterners are extremely stubborn people. They come from pioneer stock, and stay set in their ways much longer. If you were to break down those survey results further, you would find a stark difference between the rural and urban areas of those representative States (and elsewhere in the country, too). In the rural Midwest, preachers hold sway. Radio personalities like Hannity, Limbaugh, Erickson, are just the modern equivalents of old time "revivalists". They just don't travel to the communities they preach to. There's a distinction between the bible belt and the rust belt, too.
Trump will remain strong with "believers", but industrial workers are skeptics. They went with him in '16 because they were skeptical of the establishment. But, now HE'S the establishment, and they haven't got what THEY were going for. They may not vote for dems, but they're more likely, like you, to "sit this one out".
I hear you. There is a huge divide between urban and rural, no doubt. Another difference is in 2016 Hillary Clinton had all the baggage, Trump was an unknown. This time around, it will be Trump with the baggage. I like your explanation, it makes sense to me.
I'm not sure about the other southern states, but here in Georgia in the 50's, 60's, 70's and 80's we got a lot of conservative businessmen and their companies fleeing the higher state taxes and state regulations of the Northeast to resettle here. That trend has changed. Now we're getting the more liberal folks from the northeast. Guess they ran out of conservatives.
Our politics is certainly changing, as is North Carolina's to go along with Virginia's. We're certainly much more urban. Concrete and asphalt has been replacing farmland at a steady pace. I live 25 miles south of Atlanta and it is fast becoming a suburb of that city. In my county alone, I seen the population grow from around 20,000 30 years ago to close to 250,000 today. What was farm land and small towns of less than 10,000 are large towns of 50,000 with hardly no farmland at all. I was born and raised on a farm.
I suppose that is called progress, but I hate it. One of these days there will be no farmland left, Soylent Green will become a reality.