I am kind of bummed that this is the way technology is going. In my view Microsoft would be smart to keep an up to date desktop style OS (like 7) around, not only a tablet style Os (like 8). The reason for this is that unless there is some miracle breakthrough, a good portion of the industry will remain desktop dependent, due to the fact that I don't see tablet or portable hardware surpassing desktop hardware anytime soon. Serious gamers, or those using their computer for heavy duty workloads, will prefer something like 7 instead of 8 because it is optimized for a desktop computer and not a tablet or touchscreen.
TL;DR : Either a whole industry will have to adapt or Microsoft will have to keep an up to date desktop OS.
Disclaimer: this is just my personal opinion ;)