There will never be an appreciable number of people writing the kind of software that justifies the use of Ada. If your project needs it, the cost isn't a concern.
Ada is a general-purpose programming language with an emphasis on safety and contract-oriented programming. There's a lot of software written in e.g. C++ today where Ada would be perfectly justified, if only it was more widespread and accessible.
You definitely could write a lot more in Ada. The world would be a lot better off for it. Unfortunately, with the way things are going right now, I don't think it will happen. It takes a lot of active convincing to keep people from writing absolutely everything in JavaScript, so I don't think we'll be able to get to a point where Ada's ecosystem will be built out enough for it to be a common general-purpose language.
