> I haven't seen reports recently of any large migrations to Ada, Pascal or even C++ or other old (20yo+) language.
Things are quietly rewritten in Java and C# all the time. I’m sure it happens with C++ as well since the more recent quality of life improvements have landed in that language.
Java and C# are very "corporate languages". Microsoft and Sun/Oracle have done well in their marketing and manipulations. The usual philosophy is that it's easier to find programmers that know those languages, so it should be easier to support and replace programmers as needed.
It creates a kind of "self-fulfilling prophecy". "We can only find Java and C# programmers, so everything needs to be and upgraded to Java or C#. Since everything is in Java or C#, we have no choice but to keep using it. Since everything is written in Java or C#, then those are the languages I better learn." It's very hard for other languages to penetrate that bubble.
Ada, and even more so for C++, will hold on relative to the code previously written with them. But clearly, so many programmers will "hedge their bets", with also learning Java or C#.
Pascal/Object Pascal/Delphi, from back in the 1980s, was a "problem" for which big players (like AT&T, Microsoft, Sun, etc...) have arguably pushed a lot of hate and disinformation towards. There is a good argument to say that these days it's really more for independents and mavericks. Way more for Pascal programmers who managed to get themselves into positions of power, that are calling the shots or can influence what gets used.
Delphi/Embarcadero would have made the language extinct because of their short-sightedness, charging outrageous prices for its IDE/compiler to the enterprise, and developing little to no Object Pascal talent, if not for the open source projects of Free Pascal/Lazarus and PascalABC. Interestingly, a few changes in the past or future, and Object Pascal could/can be a contender. It is a viable alternative to Java or C#, but doesn't have the corporate push.
Things are quietly rewritten in Java and C# all the time. I’m sure it happens with C++ as well since the more recent quality of life improvements have landed in that language.