It makes sense. Not only is it reminiscent of the 8800gt->9800gtx scenario (down to former positioning, die size and likely price), it allows nVIDIA to reposition their lineup. Surely a GTX460 1GB and full GF104 could be clocked compete with the 6800 series. The current 1GB essentially does compete with the 6850; it's not asinine that a full gf104 clocked at ~750mhz would do the same against 6870.
Nvidia Corp. reportedly accidentally leaked its own plans to refresh its product lineup with GeForce GTX 580 graphics card. The new flagship product should start the refresh of the whole family that was confirmed by the company back in September at its GTC 2010 event.
The accidental confirmation came in the form of listing of the GeForce GTX 580 graphics board in the catalog of 3D Vision-compatible components. The leak was quickly removed, but screenshots of the page are available on various web-sites or forums (here, for example) at the moment.
Unfortunately, at the moment we know almost nothing about the GeForce GTX 580 graphics card. Semiaccurate web-site claims that the novelty is based on a new code-named GF110 graphics processing unit that has 512 stream processors along with other improvements. Given the fact that Nvidia already has experience with GF100 with 512 SPs and its costs, it is logical to expect Nvidia to maintain the number of stream processors and refine the design of the chip rather than to design a chip with higher amount of execution units.
Given the fact that Nvidia has already confirmed the refresh of the whole Fermi lineup in 2011, it is possible to expect chips with code-names like GF112, GF114, GF116 or something like this to transpire shortly.