He's playing Jazzfest so he's definitely a possibility.
Don't think he has played Roo in a while, either, so wouldn't be shocked at all if they brought him back.
Relentless7 with Ben Harper were there in 2009. I think having an album with Charlie Musselwhite makes it likely, especially since they're doing other festivals together. I'd be surprised if they're not there.
4/17 Jim James
6/8 Tallest Man On Earth
6/11 Local Natives
7/6 Bob Dylan, My Morning Jacket, and Wilco
8/15 STS9 and Umphreys McGee
10/25-27 Mountain Oasis
I'm pretty sure that somewhere in the Direct Confimation thread he came up as a no. Hopefully it changes because his set in '05 was awesome. He even talked about it in an Entertainment Weekly feature later that year.
Lucky for me I get to see him for Valentine's Day this year. Yes, that means that I don't have to make any real Valentine's Day plans and my girlfriend will still be happy!