"Sorry boss, but we're just not going to be able to meet that deadline, because, well, a language extension we were using was dropped from the language, and the syntax for some core operators was changed. Not only is our code broken, but many of the libraries we were using are broken. Don't worry, though, we're 'agile', so our unit tests will tell us when our code is working again."
Big business demands stability.
And yet they use IE... how many projects have I had to spend substantial time "fixing" because Microsoft releases a new IE...