I doubt that U2 have a contract with LiveNation that obliges them to do another three tours in the next eight years.They signed a 12 year deal with live nation in 2008 which includes handling the band's worldwide touring, merchandising, and the band's U2.com Web site. I remember reading when the deal first came out that it included 4 tours within that 12 years. How else is live nation going to make their money back. Just wait and see, and I bet they do 3 more tours by 2020.
According to the contract, I wonder what the minimum number of shows is that constitutes a tour?
Say it was fifty shows, would that mean 360 would count for two tours? There were seven legs after all.
I wonder how much it would cost to break the contract?
Anyway, I seriously doubt they will be doing three tours world wide in the next 8 years. Perhaps they only have to play a handful of shows on two continents to qualify.
They will have to break out the folk music soon and sit on bar stools, if they stand a chance.