IMO ... Pakistanis as a whole didn't go backwards, it's just that the leadership in Pakistan has gone backwards because they excluded the forward-looking types. So what you see in the old PAF documentary is an example of the "right leaders" at the time of the older generation.
However, the capable Pakistanis of today aren't managing Pakistan, but contributing to the benefit of other countries, such as the US, UK, Canada, Australia, Netherlands, Norway, Germany, etc -- we were (and still are) excluded from running Pakistan.
To illustrate this point. My maternal grandfather was studying in the US at the time of Partition. In 1948, a Pakistani mission invited him and others to a private event in DC. There, this mission said, "how would you like to manage XYZ?" The folks (all PhD candidates in various fields) who got the invites were offered spots in the nascent nuclear program, agriculture policy development, higher education, and even to manage UK and US aid programs.
Now contrast this with CPEC.
If you re-inject competent Pakistanis into leadership (at scale), you'll start seeing positive change very quickly.