Hi Gary,
You could also reach a point where your backend ABAP instance Kernel version plus SAP-BASIS component will have problems with a unsupported SAP GUI. Your W2's will leverage an Adobe Document Server, ADS, or smart form technology. You will experience rendering issues eventually.
It's a vicious circle of Desktop Office Integration. With Microsoft 8.1 and Microsoft Office 2013 there were a lot correction's pushed out in SAP GUI 7.30.
Cheers,
Dan Mead