My Canon imageCLASS 8180C works in Win 8, but I only tested for print and fax. Scanning hasn't been tried yet. However, it really wouldn't be a big deal for me to create an XP Mode, Hyper-V XP instance, or some other XP VM and scan that way if I really needed to. Win 8 (at least the PRO edition) comes with Hyper-V so you don't even need VMware to host a second O/S. However, XP Mode was free, while I suspect that a complete XP instance in Hyper-V on Win 8 won't be.
I am less concerned with printing from a Win 8 RT tablet. That might be good for e.g. a shop floor, a shipping company, or something else where you need to be mobile and also print receipts, labels, etc., but any company large enough to be doing that can potentially invest in a printer upgrade - or in x86-based tablets.