I would pay for this in a heartbeat if this was a desktop app I could use offline. On the cloud I'm not so sure. With all the stories going around HN I barely trust Facebook and Google with my photos.
Such services won't realistically be a desktop app, since that pretty much requires them to give away their service and "secret sauce" in a way that's infinitely reusable / copyable for anyone who cares enough to extract it.
The usual situation for services like this is that it either runs on their servers, or you're willing a to pay sufficiently large amount to make it worth the full standard enterprise B2B sales process, a negotiated contract incl NDAs and liability and for them to do an on-site installation. So if you're a big organization that wants to care about trade secrets or classified information, then it can be arranged, but it's not manageable for individual consumers or small businesses.
Alas, the "secret sauce" is already freely available: http://waifu2x.udp.jp/. The only real difference is the (very, very appreciable) effort to make it commercialized software. Anybody who cares enough to disassemble it for reuse could build the core tech themselves.
Edit: Actually looking at the source further it appears they also have models for photos as part of that project in addition to the model for anime.