That would be exciting! I was amazed to know that GPU could be used for other purposes than the rendering of the graphics.
As for the block chain, I wonder how much the process over the internet is affecting its overall traffic.
I don’t think it has much internet traffic compared to things such as streaming videos or other common uses. Most of “work” is computation at the client side and constant communication is not that high. Volume of transactions is also nothing compared to services such as YouTube.
GPU’s have evolved to really become a massively parallel processor, and by providing a software language by which each of those can perform some function (computation of one sort or another) the use has extended beyond 3D graphics.