FPGA can be great for solving the problems that one can't solve with custom-made silicon, but once it has to compete with it 1:1, FPGA sorely looses.
So, since GPU is so area and power intensive and since it has great players on the field that are opening gradually their documentation ( AMD and nVidia, even Intel) I fail to see any advantage of this.
Even if you open the documentation and let's say you come performancewise sufficiently close for someone to choose your solution, how would s/he escape patent suit ?
main players already have bunch of patents and capable legal teams for battle if need arises.
What do you do if you get nice and cosy letter from their legal theams ?
I don't know if there are any precedents, quick googling didn't reveal any. But I would argue that since I can make it do other things tomorrow, like calculating pi, by typing on my computer, it is software.
Then there's the selling aspect too. If you only keep it in a repo somewhere, without even selling FPGAs (or selling empty FPGAs and telling users how to load it), you should be in the clear: see ffmpeg/mplayer which are affected by approx 10^7 software patents.