"although IBM used it for some of its RS/6000 boxes"
The CHRP platform formed the basis of all RS/6000, pSeries and Power systems from the second generation 43P (the 7043 models, not the original 7248 which was a PReP model) right up to the current day.
Although modern Power systems use PCIe rather than PCI or PCI-X, they are still under the covers CHRP platforms, although they are not categorised as such any more, because it is not important. I'm sure CHRP has evolved, but it is still CHRP.
If I look at one of the Power7 systems running AIX that I help look after, I can see "devices.chrp.base.rte" along with 25 other support packages that mention chrp.And I can tell that this is not for legacy systems, because amongst them is "devices.chrp.IBM.HFI.rte", which is the support package for the HFI interconnect that does not appear on any other IBM Power server than the 9125-F2C Power 775 HPC system.
So CHRP is alive and well, but only in IBM supplied systems.
It is possible that the Power8 systems will not be CHRP, because the fundamental GX++ Power bus is no longer used as the primary system bus, and has been replaced by the PCI Express 3.0 based Coherent Attached Processor Interface (CAPI). Whether CHRP will be extended to include CAPI or replaced, I do not know.