The exact opposite of what you suggest already happened: Ada was mandated and then the mandate was revoked. It’s generally a bad idea to be the only customer of a specific product, because it increases costs.
> And the F35 and America's combat readiness would be in a better place today with Ada instead of C++
What’s the problem with the F35 and combat readiness? Many EU countries are falling over each-other to buy it.
> What’s the problem with the F35 and combat readiness?
For example, the UK would like to use its own air-to-ground missile (the spear missile) with its own F-35 jets, but it's held back by Lockheed Martin's Block 4 software update delays.
> What’s the problem with the F35 and combat readiness?
Block 4 is very delayed for starters.
The F35 was like 10 years and $50B over budget.
> Many EU countries are falling over each-other to buy it.
It's because we are obliged to want more freedom.
> Many EU countries are falling over each-other to buy it
They are not buying it for its capabilities though, but to please their US ally/bully which would have retaliated economically otherwise.
See the very recent Swiss case were theirs pilots had chosen another aircraft (the french Rafale), only to be disavowed by their politics later on.