We will know what the band will decide when they decide it. Personally, I think Phish is not a "Festival band". They're too big -- we all know phish was able to pack their own festivals, turning them into small cities -- Yeah, it'd be cool to see them sharing the bill with other bands, and I'm sure a lot of people would get turned on to Phish that wouldn't have otherwise - To me it just doesn't make sense for them to do it, I feel like the band likes to do things their way and if they can throw their own festival and be in control of all of the logistics and production of the event they would choose that over being put into a "slot" at a mega-fest such as 'roo or rothbury. Just my two cents, who knows what the band will do. They never cease to surprise.