This is pretty much how the stock Android keyboard works. It's been able to spot missed keys since at least Ice Cream Sandwich - e.g. I just typed "kettrt" and it's suggesting "letter" as a correction. Since Jelly Bean it's also had some bigram support too (guesses the next word based on the previous without you typing anything).

Aside from the "typing without a keyboard" part, it's not obvious from the video how Fleksy differs from this, but the focus on blind users probably makes a difference.