It is very hard to discuss the future without mentioning what exists. Also, most of the future has already been invented, and was merely ignored at the time. I can probably mention a dozen features that appeared previously, or at least were specified in detail, and somehow never got into the mainstream languages. It is highly arrogant to imagine for example that John Backus, Niklaus Wirth, and others didn't invent all sorts of things that are still considered "future". In fact you can make a stellar product just by going back at the past work that was glossed over for some reason. There are so many fascinating things in engineering history that have been forgotten or derailed. The Chrysler Turbine Car, Geopolymerization of stone of the Great Pyramid at Giza, Tensegrity, PROLOG deductive capabilities, etc.