Going out on a ledge, 100 years is a really long time technologically speaking... As such, I don't think we'll literally program computers in 100 years so much

Going out on a ledge, 100 years is a really long time technologically speaking... As such, I don't think we'll literally program computers in 100 years so much as think about problems whilst connected to some sort of cybernetic system. The now obsolete act of programming itself will be abstracted away in the same way a language like Python abstracts way assembler, cache, and memory management today. 50 years ago code was still being submitted with punch cards. In 1971, my father got a 110 baud model 33-ASR teletype that drastically simplified coding and provided paper tape for offline storage. Compare and contrast with today. In such a system your wetware and the hardware will collaborate in the same way that groups of people brainstorm ideas, resulting in code that just seems to write itself driven by one's thoughts. What AI will have become by then will be more then capable of running such a program through bajillions of chaos monkey simulated scenarios instead of a hand-crafted set of unit tests. As to what that language actually is, just what kris-s said: easy parallelism, easy networking, and easy access to storage in a way that the HW itself does all the management implicitly and emergently. But I doubt humans will write this code, I think the compiler guys will finally win this by building something like the above, where hand-coding such a widget would be insanely tedious for mostly meager performance gains (unless you're an infinitely patient machine that can go arbitrarily parallel). The current DL ASIC war combined with the framework compiler arms race just beginning now ought to give us an early preview of what's to come.