It'll have to wait, though. For the moment the group is planning a stadium tour even larger than its gargantuan Zoo TV tour, one which will take them to 40 countries over 18 months, and will arrive here at the Metrodome on Oct. 29. It's billed as the Pop Mart tour, with an insignia like half of McDonald's golden arches, and is supposed to feature a 12-foot electric olive on a 100-foot toothpick, among other things. For all the kitsch, I bet it'll be full of earnest music. And if there's no true cultural center-stage for a band to hold anymore, I bet that, on any given night on the tour, U2 will feel like there is.