MBU-5 was made standard-issue in the late 1980s and early 1990s, but the PAF didn't buy the MBU-12 in the 1990s (when it was popular). Though a few MBU-12s were ordered in the early 2000s, the PAF opted to standardize on the MBU-20/23. For the most part, it's been on the 20/23.
The interesting now would be to see how it adds HMD/S to the JF-17. One option is replacing the whole helmet, but another is taking the JHMCS and Scorpion route of developing a HMD/S that can fit to the HGU-55/P. Could be very interesting if they can pull that off.