Personally I welcome a certain tempering of the "binary compatibility for ever" line. There
are so many other reasons why it will be hard to get e.g. a binary build for Linux 0.99 to run
on a current system that keeping the kernel binary interfaces that stable seems a bit silly.
If you really need to run that sort of binary you can still go for an emulation or virtualisation
solution of one shape or another, and there are other places compatibility layers can be kept
than inside the security-critical kernel space.