According to a December 23rd tweet by Portishead's Geoff Barrow, Portishead are "doing some split headline shows with arcade fire next year , I'm really looking forward to it..proper band!!" That won't be the promised U.S. Portishead tour though as Geoff later explained "What i mean is that We will be playing with AF at some point next year it's not a tour though!! Sorry." and "The shows with AF are festivals in Europe or I think they are? Hope that helps!" Oh well, I think (stay tuned for the rest of the American dates when they are announced though).
As reported by Pitchfork, "there's going to be more [Jeff Mangum] shows scheduled in the future." Stay tuned for that too.