Mantaining multiple kernels would only add overhead on developers' work, and bloating /boot.
I don't really get that. I'm no expert in using pacman or writing PKGBUILDs, but I can very readily imagine a mechanism that on each rolling release update to the kernel, moves the current kernel on the users system to say 'kernel-previous', and puts the update in place for 'kernel'. Add a line to grub to reflect the two kernel-versions (current and previous) and handle this with symlinks so that the actual kernel + libs and so on can have version names. On the other hand, I have never had a kernel-update completely break my system, so the question really is, if automation of such functionality is needed. After all, you really should compile your own kernels, and keep backups around just in case you break something there yourself... IMHO Tom