So in effect, aside from the minor expected performance bump, the 10-core processor is a more expensive addition to the lineup as opposed to adding cores across the range at the same price point.
Doesn't make the upgrade worth it from any perspective really, but that's not really who they're aiming at.
I'll eat my hat if Intel drop the price of the two hex cores and the octo core below the current level of pricing by much especially at the hex core end....
I have posted about this before but look at it from Intel's point of view if the 6700k sells for just under £300 in the uk then the 6800k (entry level broadwell-e hex - think 5820k replacement) will cost at least £330-350. Given that there are still two hex cores in the broadwell-e lineup the 6850k (think 5930k replacement) will almost certainly be differentiated from the 6800k by a circa 200mhz stock clock difference and full vs reduced pci-e lane count (ala 5820k/28 lanes vs 5930k/40 lanes) otherwise there will not be enough difference between the hex cores to make it worth it as Intel know that both the 6800k and 6850k will overclock on average to similar levels (like the 5820k and 5930k do)
Therefore it's reasonable to expect that the 6850k will cost similar money or a bit more than the 5930k does now... Say circa £500. Now if Intel were to release the deca core CPU at the same price point as the 5960x at about £800-900 that does not leave that much space to squeeze in the octo core broadwell-e CPU between the deca core and the upper level hex.
Until Zen comes out Intel have no chance of competition at this level and no incentive to drop prices. The four sku broadwell lineup over the three sku haswell-e lineup is a clear indication I believe that Intel do intend to insert a new Premium price point for there incoming deca core CPU. Its supply is likely to be quite limited and Intel know that some people will still buy it at £1200+.....