Didn't
Erinyes say that even the big, proper Maxwell will be on 28nm? By late 2015 16nmFF will likely commercially viable for GPUs for mid-later 2016 unless they plan to make GP100, GP104, GP106 or whatever the heck those are called be released very late 2016 or 2017. I can see them doing a 870 later this year and then 880/880 Ti 1H 2015, with the former being 256-bit memory bus and the latter 384-bit bus. I just cannot see the HPC segement waiting for a 512-bit bus as they are primarily interested CUDA cores but then again I'm likely being ignorant and dumb.
Economics and laws of physics from the looks of it say that 20nmSoC at TSMC is not that good for High performance components and TSMC 16nmFF is based on TSMC's 20nm which will be more of a step up from 28nm and be more viable.