good topic!
all speculative of course, but great fun. ;-)
personally, ...i don't think there will be characters as in-your-face as macphisto, mirrorball man or the popmart boxer...
i get the feeling from what we've heard, and seen in the Lanois documentary, that their next "incarnation" will be a cross between the Unforgettable Fire and Achtung Baby in sound, with some new elements thrown in.
The sound will be atmospheric and edgy (a la AB) at the same time.
And though this might seem like a contradiction at first, i think they'll also delve into "roots" music- whereas with JT and R&H they immersed themselves in American music- blues, gospel, etc- i think this time they'll pull inspiration from even older forms of music- we all know they've been playing with traditional Moroccan musicians. A quote from Bono surfaced a few months ago where he talked about the connection between traditional middle eastern and irish melodies.
I'd love to see some brilliant combination of those four sounds- atmospheric rock, edgy "AB" rock, traditional middle eastern, traditional irish.
as they surround themselves with new sounds, the muses will channel themselves through Bono- we'll see some new characters- maybe based on ancient or medieval musicians or poets, and some others from the future...