The new hotplug-20040923-r2.ebuild still mentions coldplug in its ewarn. Just as the hotplug initscript is dead and buried, the coldplug package is at least deprecated, as it has been folded into udev.
It appears this hotplug is stable, but the newest for ~arch as well, while udev is spread out rather farther, udev-90 including coldplug ~arch, udev-87 or even old 79-r1 stable, both of which don't yet fold in coldplug. Perhaps then the ewarn wording needs to mention coldplug for udev earlier than 89, but that it's folded into udev for 89 and later?
(Priority trivial since it's ewarn wording only.)
Yeah, it's a mess of dependancies, will work on fixing this up.
sys-apps/hotplug is useless with any recent udev version, and 2.4 kernels are no longer supported. Unmerge it and move on.