DC a suburb of New York?! Only if your definition of suburb extends 200 miles beyond a city’s borders.
In all seriousness, clearly Florida does not mean suburb in the conventional sense. And his point is an interesting one: technology enables some of New York’s elite to call DC home.
This pattern, if at all significant, is a product of Flat and Spiky Worlds. It is also an excellent example of urban pairing, a prospect The Urbanophile is exploring concerning Chicago and Indianapolis. The goal of this emerging economic geography is to reduce costs of proximity productivity (i.e. innovation). Second or third tier cities provide sufficient knowledge density along with superior connectivity to the urban core higher up in the mega-regional hierarchy, but at greatly reduced overhead.
If DC can be a "suburb" for NYC, then I think Pittsburgh is the bedroom community for DC. Moving even further down this food chain, I'm currently exploring opportunities in Youngstown as a way to R2P. Both Youngstown and DC offer an avenue for moving back home and getting more involved in Rust Belt redevelopment.