I reckon U2 would easily sell out or nearly sell out another 80+ arena shows with similar ticket prices if they tour again in 2017, as I expect. But I think they'll play stadiums next time with a new stage show, and if they charge lower prices I think they'll do well. A new album will certainly help to sell tickets, particularly if the new music is commercially successful, and this will keep hardcore fans interested, and the hits/warhorses will keep the casual concert goers satisfied. There's certainly room for one or two rarities in their sets so I hope they work them into their next show.