Technically, Dave, BlindType isn't predictive text as you actually need to type out all the letters in the word for the algorithm to select the word you're trying to type. Predictive text as it exists today tries to guess what word you're going for with the fewest letters possible.
The trick in BlindType is that it tracks the points in space where you are typing to figure out what letters you were trying to hit against a word dictionary. Presumably, this can be adapted to any language that uses the QWERTY keyboard since it's just a matter of changing the dictionary underneath. Unlike most predictive text keyboard that spell correct at the same time, if you misspell the word in BlindType, it won't match.
The most intriguing part of the demo is inputting characters with BlindType with an invisible keyboard. Now you don't have to up half the screen with a virtual keyboard. And if you can do that, you can type without even looking at the keyboard.