I wanna agree with this, but...
We've long since moved on past 2e's setting splat.
In 3.X, we had (not counting a couple of licensed products like OA, RL or DL) a total of two "specific" campaign settings: Eberron and Forgotten Realms (the third, Greyhawk, was hidden in the core and slowly morphed from anything canonically Greyhawk by the time 3.5 rolled around). WotC made maybe 10 book each for them, the bulk of the 3.X line was "generic D&D" Even towards the end, Realms and Eberron material lost its unique look and began to resemble core lines (witness Races of Eberron). There was no Planescape book, there was Planar Handbook. There was no Ravenloft book, there was Heroes of Horror. There was no Dark Sun, there was Sandstorm and the Expanded Psionics Handbook.
4e took it further: three settings (Realms, Eberron, and Dark Sun) got a setting book, a player guide, and a module (DS got a Monster Manual instead of splitting the DM/PC guides). The remaining amount of 4e's releases WERE generic. And everything was designed to work together, which is why Dark Sun PCs no longer were generated with 4d4+4 for stats.
The ghetto of "supplements for supplements" died in late 3.5, but was dying come the end of 2e (RL and PS in specific started getting releases under the Core supplement line come Carnival (RL) and Warriors of Heaven (PS). WotC has been making generic D&D material (out of or replacing settings) for 15 years; this is hardly re-inventing the wheel.
Which brings me back to my original thought: how much less support can you give them and claim they are still supported? Planescape hasn't seen a proper PS* book since 97, Ravenloft hasn't had a new release** since 2006, same with Dragonlance. Mystara and Birthright died in 1996. Proper Greyhawk*** in 2002. Eberron saw its last book support in 2009. Everything else WotC has made is either generic or Realms (and Realms only in the form of adventures). You can't get any more "one brand D&D" than this unless you make all of it into a single setting (*coughNentirValecough*).
I really wish the interview could have honed in on setting support, since WotC SAYS it wants to support all settings (and has made some gestures for that, such as mentions in the Core books and the Eberron UA) but so far hasn't told us if we are going to see campaign settings, a giant book of settings, UA articles, or just occasional references to other worlds strung through future books for those diehards who collected material during 1982-2010.
* There have been planar books and mentions of Sigil throughout 3e and 4e, but neither carried PS's tone or style, rather returning to the older idea of "Planes where big monsters live".
** Expedition to Castle Ravenloft doesn't count, as it deals mostly with the original I6 module and famously gets canon wrong in an attempt to revise the classic module.
*** Ignoring Expedition to Castle Greyhawk, a love-letter to GH for sure, but very much a one-off rather than anything resembling setting support.