First even Thiel agrees there isn't lack of innovation in computing.
Alan Kay asks about big ideas, not about innovation. I'm pretty sure that if you look at research papers you'll find amazing ideas that within a 5/10/30 years time will be important(but we can't tell, not until we worked hard to make them work).
Just of the top of my head, there are many potential amazing ideas: look at literature based discovery, alan kay's project that tries to build full os + apps in less than 20KLOC, "naked objects" and meredith patterson's work on parsing and security[1].