The guy from "Pair" in the first episode of "Planet of the Apps" [https://www.planetoftheapps.com/en-us] tried to make a similar SDK his main business model but eventually failed to get the fundings from the VC.

I hope in the end he decided to stick his focus on the app (which is quite amazing), otherwise he's in big trouble now!

I really think that a lot of new apps will come out in this space, now that the technology is much more approachable.