I wonder what google would have to say since it's built from deep dream experience. Also it was recently improved with newer tech which may very well be non infringing
eh most computer now have some good muscle. also it's an iterative process so you can show a meaningful progress bar to user even if it takes an hour or so people wouldn't complain. and for many it would take minutes - one just need to set the expectations straight.
"By increasing the server memory to 27GB I manage to create 1024px images on CPU - seven hours per image" - http://spiceprogram.org/artcorn/
And the GPU version requires amounts of video memory that generally do not exist for anything else than research or GPGPU purposes. With 4GB of VRAM you might get a 920x690 image processed in under 1 hour, using recent optimizations added to the neural-style repo.
So a standalone iOS version seems pretty useless. A standalone Windows version might appeal to people with gaming rigs but without the technical knowledge or determination to install neural-style in its current form. It certainly has potential, just not as huge as the cloud version.
If you were a serious graphic design professional might not you already have an i7 or a xeon rig with SLI already set up, and be accustomed to leaving a render running overnight?
As for an easy standalone version, it wouldn't have huge potential, considering the inevitable GPU / computing power requirements.