Anyone with knowledge of the area want to compare to the income map? At least from a glance, it doesn't so much look to be wealthy suburban Republicans defecting to Clinton as much as Atlanta being even more diverse than it was four years ago...
I'd argue that the map as scaled is misleading: the handful of precincts that are showing >$250k really make it harder to determine income's effects in the election. It's Atlanta, not New York: a lot of people here who have $150k household incomes are going to be considerably better off than a household making $300k in a larger city. There's a lot of relative affluence in the $100-200k range, and that's probably where the shifts - at least in nominal terms - would be the largest and most influential. Perhaps a different color scheme - since I don't think you can actually filter down the range of incomes on the map - would show it more accurately.
The areas of "expansion" for Democrats throughout the metro in this election and prior are happening largely along interstates and major highways, and follow a very predictable pattern of minority movement that has been occurring for a long time. However, many of these areas would never be Democratic enough on their own to move without some substantial swings among white voters there, regardless of income. You'll see the precursor for the 2016 map by precinct in the 2008 map (below), but the explosion of R-to-D precincts in this election can't be explained by minority demographics alone.
If you take a gander at the swings by county for the metro, you'll notice that the heaviest swings were in areas in the far northeast (and outside) of the OP's map: Forsyth, Cherokee, Gwinnett.
While Gwinnett has a substantial minority population - much of it Latino and Asian - Forsyth and Cherokee do not, and much like Gwinnett, a lot of it is Latino/Asian, meaning that it is nowhere nearly as Democratic as much of the inner metro minority population and simultaneously not as likely to vote in full force. With that being said, Latino turnout
among registered voters in Georgia this cycle improved substantially, with Latino turnout being higher than black voter turnout in many counties.
Here's my animated GIF of presidential/gubernatorial results by precinct from 2002-2016. You can get an up-close and personal view of the metro if you open in new tab/zoom in:
