I can't imagine there is much motivation for them to not have a fourth day this year. I guess I'll throw out the suggestion that they're going to announce RHCP as the first headliner. If that happens, I will most likely not be attending friday.
If RHCP did get booked I have a feeling they could turn out to be a lot like the Foos. Everyone knows a lot of their songs and they have been around for ages so they probably know how to put on a good show. Or they could suck.
Regardless, I would see them and wouldnt be too pissed if they got announced.