It makes sense considering the EVO 4G LTE’s debut is just around the corner, but it is interesting that it was just here one day, gone the next. The folk over at Android Police reached out to Sprint to find out what happened to the Android device. Sprint responded by saying,
So there you have it, the HTC EVO 3D is officially entering retirement. If for some reason you had your heart set on getting this device, be sure to call you local Sprint store or take advantage of the Amazon sale before the end of the month.
source: Android Police