Not an incentive as in:
- Pre-DRM I could install anything, anywhere, any time.
- How many people (other than journo's) game on more than one machine? Not many I'm betting, because how many people can afford to have two gaming PCs capable of running, say, AC2 on decent settings?
Its certainly not enough to force people into a 100% connection situation. I also doubt that anyone gaming on a PC would have any trouble finding out where a save file goes. And if you can't be arsed with third-party software, why not email the save in an attachment? Or use a memory stick?
Steam has the only incentives, and Valve has plans for cloud-gaming for that anyway; and for those without a 'net connection that's still not an incentive, just an added bonus for those with one.