Karl writes 

> , as far as I can see, essentially the entire LaTeX-using world
> will be broken, and that will harm everyone.  

Furthermore, and maybe my most important point, is that almost the entirety of that world is very far from any TeX-related mailing lists, user groups, blogs, etc etc etc.  

Also, even the small(??) parts of it that I occasionally move in are estimated now to total over a million users and they are more and more using it not just to format whole documents for paper-like output but as input to a large range of computational, information and communication tools that need to interact smoothly with more standard formatting uses.