What is that monstrosity in the middle of the picture? Is it a Gnome? Beware - a dual rapier wielding gnome paladin!The point is well made though. If they are going to make changes to the setting, walking softly is definitely the easier way to go. It's much, MUCH easier to slip in small changes than big ones. Just look at the 5e Monster Manual and then compare it to the 3e Monster Manual to see how much you can change the game without ruffing feathers.
And, frankly, there are a million ways to slip in something as minor as a new PC race into the game. They did it quite well with Tieflings in GoS for example. That tiefling isn't a smuggler. She's there as the imperial representative of Iuz, waving the flag and all, legally buying food supplies to ship home. This is all above board and legal and everyone knows it.
You could easily add in another PC race in a similar fashion. The notion that Race X (whether it's Dragonborn or Lupins or whatever) have always been in the setting, but, marginalized and living in small, isolated communities on the fringes. They haven't been mentioned before because, well, they're just not that important in the larger picture. That's probably the simplest solution.
Oh, and just because everyone else is doing the mic drops, I'd point out that Dragonborn do appear in the artwork for Saltmarsh, so, they are canon in Greyhawk. And, yes, GoS is canonically Greyhawk despite the fact that there are sidebars for placing it in other settings. It is NOT a generic product. It is SPECIFICALLY placed in Greyhawk.