I downloaded the latest 777 update and no, it doesn't seem PMDG has changed anything in the wheel chocks, and GSX correctly detects them to be released when starting Pushback.
However, GSX has another feature, which we currently used only in the Aerosoft Airbus, and the FS Labs A320, which is a custom parking brake control to be used as an alternative as the parking brakes, so you can activate the GSX menu on the parking with wheel chocks only.
The latest Live Update adds this feature for PMDG planes too.