Update: We've gotten official word from Sprint - the EVO 3D is officially on the way out:
The award-winning HTC EVO 3D is no longer available through Sprint.com. Quantities are limited, but customer can still get HTC EVO 3D at Sprint Stores nationwide.
So here's an interesting little fact: if you go to Sprint's site right now and look for the EVO 3D, you won't find it. Really. Go look for yourself, we'll wait.
Back? Told you it was gone. The bigger question here, though, is why. And for that, we don't quite have a good answer. Perhaps Sprint said "you know what, we don't like this thing anymore.