Microware OS9 (for the 6809/68000) used to have device modules. They were small files that were tweaked for the machine that could be on disk on in ROM. A serial driver device module would say something like "use chip driver mc68681.drv, interrupt 4 and memory i/o of 0x80008".
That's how I expect Microchannel could have evolved had IBM been smarter on the licensing front. Those "reference diskettes" would have eventually evolved into EPROMs on the adapter cards, with the device configuration and binaries for drivers on the device itself. At this point it's to late to implement such a thing even in PCIe.