Even with the Futures ecosystem having a massive change first with the std::future impls and then with async/await, there are backward compatible libraries that

Even with the Futures ecosystem having a massive change first with the std::future impls and then with async/await, there are backward compatible libraries that make it possible to inter-operate between the two. You probably don’t want to live like that forever, but it’s a way of not being “required” to upgrade large code bases.