- 2.6.<odd>: still a stable kernel, but accept bigger changes leading up
to it (timeframe: a month or two).
- 2.<odd>.x: aim for big changes that may destabilize the kernel for
several releases (timeframe: a year or two)
- <odd>.x.x: Linus went crazy, broke absolutely _everything_, and rewrote
the kernel to be a microkernel using a special message-passing version
of Visual Basic. (timeframe: "we expect that he will be released from
the mental institution in a decade or two").