They'll probably swing left again. However, really high income places did not swing that much from 2016 to 2020, it was really the generic middle to upper middle class suburb that swung a lot. None of the third party options seem appealing to them. If the Libertarian ticket had someone high profile then I could see a big vote, but Kennedy is overtly appealing to lower SES demographics. Someone like John Anderson would get 20% though.
I think one difference between high income suburbs and upper-middle income suburbs is that higher-income suburbs generally have very slow growth and turnover in addition to high turnout - the 2016 electorate and 2020 electorates in these types of places were likely very similar. You also have strict zoning in these communities which means very few if any new homes were added since 2016.
In these upper-middle-class suburbs (think much of Collin County TX for instance), you have much higher turnover. Additionally, we saw big jumps in turnout, we see rapidly increasing number of homes being built, and census numbers suggests these types of places are rapidly getting more diverse while the wealthiest communities remain very white. So it's reasonable to assume the 2020 electorate was very different and likely more Dem favorable than the 2016 electorate in these middle/upper-middle class type suburbs.
