If, as there, one swipe gesture per letter is allowable, rather than a gesture encompassing a whole word, then things like Thumb-Key become options.

* https://github.com/dessalines/thumb-key

It has a similar sort of 'It doesn't have to have 26 keys on something the size and shape of a mobile 'phone.' thinking as 8vim has, whilst raising a good 'You know 'phones worked fine with a 3 by 4 grid for 60 years, ne?' point, but adding a modern twist of 'We can swipe, in the 21st century.' to the old notion of multiple letters on a button.

There are still these people thinking outside of the typewriter-keyboard-on-a-'phone box. (-: