I disagree. A touchback would put the ball on the 25. Unless you are kicking to Hester, I think most teams believe that they can stop someone before the 25 yard line because they will be able to put much more height on the kick. There will not be a noticeable drop-off in the number of returns.
I would think that, with the shorter distance, they will kick the ball higher - leaving less room for a return. Kick-offs could become like punts, where the coverage team is racing down to meet the returner when he catches the ball...