For the past few generations, NVIDIA has been roughly trying to release a new architecture with a new process node, and release a refresh the following year. This ran into a hitch as Maxwell was delayed a year, apart from the GTX 750 Ti, and then pushed back to the same 28nm process that Kepler utilized. Pascal caught up with 16nm, although we know that some hard, physical limitations are right around the corner. The lattice spacing for silicon at room temperature is around ~0.5nm, so we're talking about features the size of ~the low 30s of atoms in width.
This rumor claims that NVIDIA is not trying to go with 10nm for Volta. Instead, it will take place on the same, 16nm node that Pascal is currently occupying. This is quite interesting, because GPUs scale quite well with complexity changes, as they have many features with a relatively low clock rate, so the only real ways to increase performance are to make the existing architecture more efficient, or make a larger chip.
That said, GP100 leaves a lot of room on the table for an FP32-optimized, ~600mm2 part to crush its performance at the high end, similar to how GM200 replaced GK110. The rumored GP102, expected in the ~450mm2 range for Titan or GTX 1080 Ti-style parts, has some room to grow. Like GM200, however, it would also be unappealing to GPU compute users who need FP64. If this is what is going on, and we're totally just speculating at the moment, it would signal that enterprise customers should expect a new GPGPU card every second gaming generation.
That is, of course, unless NVIDIA recognized ways to make the Maxwell-based architecture significantly more die-space efficient in Volta. Clocks could get higher, or the circuits themselves could get simpler. You would think that, especially in the latter case, they would have integrated those ideas into Maxwell and Pascal, though; but, like HBM2 memory, there might have been a reason why they couldn't.
We'll need to wait and see. The entire rumor could be crap, who knows?