I don't know what the systems programming language of the 22nd century will look like, but I do know that it will be called C.
On other OSes, it really depends on how Apple, Google and Microsoft do their work of "our way or the highway" regarding pushing their safe alternatives.
So for C this would be 44 more years from now, but it gets another extra year for every year it survives, so it isn't far fetched to think C will be around in 2100.