Just read both the dark matter paper and the dark energy paper on Steinhardt's site. It seems to me that the cyclic universe of Steinhardt is perhaps a one dimensional of the larger 3 space dimension world. If so, then I expect that each universe expands until it merges with the larger universe. Just a guess as the need for universe renewal is met by black hole creation rather than brane collision. Dark energy being unstable is probably still true to some extent but that recollapse is not. I wonder if the two time dimensions then become aligned at merger.

wanda