I don't think anyone here is unaware of the numbers he has put up thus far in his career. He has rushed for 1,228/2,006/1,364 in his three seasons in the league on 251/358/316 carries. So if he is here from the start of the season, and doesn't get injured, there is no doubt he goes for at least 1,300 yards.
I really hope that his carry number is south of 300 this season. While this preseason hasn't made this team need Chris Johnson any less, it has shown that the Titans have a couple of guys that can run the ball outside of CJ. That will bode well for the long term viability of CJ2K's career.
All of that being said, I am setting the over/under at 1,350.5 yards.