There's no doubt that the tide is shifting but when you look at districts like SC-05 or MT-AL it's clear that this has more to do with the national environment we're in than anything of a sunbelt or wealthy college educated whites trending Democrat.
The GOP rose from the dead after Obama's initial victory and claimed a ton of seats they hadn't held for a long time, many in over a century, and Democrats never got them back.
I just don't see why their inroads into suburbia are different, and only temporary. Especially after we are seeing the numbers stick so far. At the very least, right now, there is no good evidence to suggest one theory is more correct than the other, no?
I think the ultimate takeaway is that Obama-Trump vs Romney-Clinton/Rust belt vs Sunbelt/etc. it's all just building infrastructure for the future. The Democrats since Reagan have only taken back significant political power when the economy is in a downturn (1992, 2008, etc.) even 2006 was caused in part by Bush threatening to privatize SS. This has been a constant theme with Democratic victories in this GOP alignment.
Most people don't think critically about trends or momentum shifting like us atlas nerds do. Your average American just sees that every single special election race that's been (in part) a referendum on Trump go down for the Democratic candidate 6 times in a row now. Most are not gonna sit down and try to rationalize what they saw with trends or anything like that; they're just gonna become demoralized seeing this unfold.
TD was right. Democrats aren't coming back until sh*t hits the fan with an economic crisis. Trump's institutional and civic instability clearly isn't enough to win the back the House alone. We can build infrastructure for the future races wherever Democrats happen to become competitive. But for the time being these kind of voters be they rural, suburban, college educated or noncollege educated, etc. are just gonna default to their partisan lines and belief that big government is horrible (at least philosophically) until an economic crisis hits and hits hard. I've realized that that's the only way these voters shift to the Democrats and shift long term.