I think touchscreens and development go together well, but perhaps not in the way you're imagining. The best thing about a touchscreen is that generating any symbol is equivalent in complexity to generating any other. Unlike real keyboards, which have fixed symbols in fixed positions, a virtual keyboard can be as large and complex as you want—if you run out of space on one "layer", you can just add another set. This would make a language like APL perefect for mobile development, especially if combined with some manipulable visualization of the resulting parse tree (I.e. What most visual PLs try to be.)