Divergence since 2006

The Manhattan market is a different beast, no doubt, but generally it roughly follows the nationwide market. Compare the StreetEasy Condo index and the Case-Shiller pre-2006 numbers and you'll see they're moving the same way. Then they completely split in 2006 into the end of 2008. CS basically gave back all it's 2000s gains while SE kept rising before moving basically sideways and now the Manhattan market is 50-100% higher than it would be if it followed the nationwide trends! The SE index has started moving in line with CS again, but it's coming from a tremendously higher point. Is the Manhattan market in for a precipitous drop or has it reached a new plateau above the nationwide numbers? More evidence of a widening gap between the haves and the have-nots?