I just don't see why their inroads into suburbia are different, and only temporary.
The difference being that the republicans had been winning those blue dog districts for about a decade on the presidential level by the time 2010 came around, while the democrats have only won these suburban districts once under a presidential election, which happened under an extremely unusual republican candidate.
So the idea that these suburban gains will only be temporary is a pretty logical conclusion to make.
Nate Cohn
pointed out that 13 of the 15 most educated districts are represented by Democrats, and the two remaining trended strongly D in 2016, so I kind of doubt this is temporary. Democrats have also been winning some Republican-held suburban districts in presidential elections for a number of cycles in a row, granted, none of them I can think of are in the south (except FL-27, which is different). See CA-10, CA-21, NY-24, MN-03, NJ-07, and WA-08
