Not good news for programming language enthusiasts. Presumably the purpose of this measure is to combat Adobe. I have no love for Adobe either these days, but as a software developer I don't want to be a pawn in some corporate feud. Why should Apple care what languages and tools we use? Publish the API spec and we'll follow it.
Annoying developers is no way to promote your platform. There's a certain class of developers that will build for whatever platforms are dominant – in order to reach the most users. There's another class that will primarily target platforms they themselves use and love. Which class produces the most compelling, innovative, game-changing applications? We leave that as an exercise for the reader.