"World’s First 1k-Processor Chip, Powered by a Single AA Battery (2016)"
https://news.ycombinator.com/item?id=26140957
...Might make a good candidate for a future GPU!
...As might any massively-parallel "CPU" architecture, for example, the Adapteva Parallella:
https://en.wikipedia.org/wiki/Adapteva
>"The 16-core Parallella has roughly 5.0 GFLOPs/W, and the 64-core Epiphany-IV made with 28 nm estimated as 50 GFLOPs/W (single-precision),[27] and 32-board system based on them has 15 GFLOPS/W.[28] For comparison, top GPUs from AMD and Nvidia reached 10 GFLOPs/W for single-precision in 2009–2011 timeframe.[29]"
In other words, whenever you hear about a CPU with a "massive amount of cores" -- think "could make a great GPU", or "could make a great GPU with the right adjustments" -- from this point forward!
In other words, any massively parallel multi-core CPU architecture -- becomes or can become -- a candidate architecture to become a GPU -- with further changes/optimizations...