Yeah but if you take into account the type of memory bus needed (the 2900 was over the top) the rest all fit into the expected pattern, the 680 doesn't. While what I posted is all conjecture this isn't all I'm basing it on - but thats a lot longer story. For instance if you dig into the older drivers especially early leaks they also tell the same story, stuff designated under what was originally mid-range codes, etc.
That doesn't mean much though, because this is the first time that nVidia have produced a different chip solely for HPC sector, they'd have to call the chip something, right?
Their best chip, 110, their second best chip, 104 and so on. It doesn't denote that the cards based on the 104 are supposed to be "mid range", just that it's no longer the highest chip they produce.
The power consumption and performance of the 680s over the 580s is in line with what we'd expect for a generational bump, the performance from a GK110 based chip, well it doesn't make sense that it was ever indended to be for main stream desktop GPUs.
Plus, you can see that nVidia have been dropping the memory bus each time a new gen has come out, down from 512, they have very clearly been trying to reduce the cost of manufacture of their products.
The 256 bus on the GTX 680 and 670 was entirely intentional, and doesn't mean it was midranged, because AMD got the "jump" on them, and nVidia had plenty of time to respond, in fact, nVidia would have likely had info on the 7900s long before it was publicly available too.
If nVidia wanted to put the GK104 on a 384 bit PCB, they could have very well done so, the same way AMD put the Tahiti GPUs on the 7870 PCBs.