Following up on my post from above, I booted a live environment, chrooted into my RAID, force-installed the kernel, then added the preset to the mkinicpio config to force it to create the image for the current kernel. After rebooting, I've got my system back.
I've got an unusual system, but still hope this helps someone else.
I expect this to be fixed once the new Kernel hits the mirrors. Thanks @greysky for that.