Three main topics are developed in the last development update posted by Robert S. Randazzo, founder manager of PMDG team.
PMDG 737 NGXu BBJ Expansion package : Their BBJ/BBJ2 models will include animated airstairs, and other technical modification like extended range fuel tanks.
PMDG 777 Update : the FREE update is still in development to bring Global Flight Operations, new animations and improved performance. Tests will start at the beginning of next month in October.
PMDG 737NG3 for MSFS : Not to be expected before quarter 3 of 2021, because the integration of the needed features in the core system of MSFS is slower than expected. Anyway, they seem to work closely with MSFS makers at Asobo Studios.