Saints fan here. As of now (things are still really fluid in my rankings) I have him as WR29. 67 receptions 924 yards, 6 touchdowns. He'll still be an extremely valuable and solid player in "real life", but not so much as a fantasy player, IMO. Both Payton and Brees love to use the TE, and the Saints now have a true pass-catching TE who can make things happen on his own in Eric Johnson. He'll steal some of the targets. Bush is going to be an even greater factor this year, and I expect his touches to go up. Meachem will see some touches, and Brees can't ignore the gamebreaking ability of Devery Henderson.
Further, I think the defense will be noticeably better. Not top 10 or anything, but better, with the additions of MLB Brian Simmons, FS Kevin Kaesviharn, the return of 2006 2nd round pick Roman Harper (who was playing like the MVP of our defense before his injury), CB Jason David, and to a lesser extent some rotational additions to the defensive line.
I'm expecting Payton to lean on the running game a little more than last year. Even Antonio Pittman should get some touches.
I think Colston's touches will go down by about 5, and his yards per reception will go down a little bit as well. He had a couple of flukey long plays last year (see: TD vs. Carolina), and defenses will be paying more attention to him this year.
Honestly, the only Saints player I like better than their ADP is Reggie Bush. And that hurts to say, because he's probably my least favorite player on the team.
I have Brees as QB4, Colston as WR29, Reggie as RB7, and Deuce as RB21