Everyone should do what I just did and go on the MyTesla page and voice our concerns to corporate. They recently updated the myTesla page and added a section for "inquiries" which can be sent to the Tesla support team or directly to "Tesla's executive team". I just sent the following to both Tesla groups, I suggest everyone else should do the same so that we may get a response! Feel free to copy and modify my message below as needed.
"There are many many people on the forums discussing uncorking of Model X and Model S cars build before the speed increase. People are saying that Tesla is allowing uncorking of cars delivered after July 1 2017, and that a firmware update is increasing 0-60. People are angry saying most vehicles including all AWD vehicles appear to be uncorkable since Tesla inventory cars and cars produced very early in 2017, 2016 and even CPO's are all being uncorked so long as they've been delivered after July 1. Is it possible to get an uncork for my MX 75D??? I've loved Tesla for a long time but it's seeming very obvious to everyone that Tesla is holding back to old owners and it's really upsetting!"