I don't think the price for PCs will matter. You can always grab a bluetooth keyboard if you want to type something out, and there are even web based IDEs available, which means that you're not limited to platform. Right now, you can add a keyboard to your droid or iphone and start hacking away.
Additionally, the programming experience is in many ways focused too much on the text based code itself, and less on the act of creation. It may be that changing the PC/developer interface causes a revolution in the way that people program.
Yes, you are. The parent was arguing that PC hardware would become specialized high $ developer only equipment, but as you say all you need to recreate a PC from a mobile device are a couple of peripherals.
Additionally, the programming experience is in many ways focused too much on the text based code itself, and less on the act of creation. It may be that changing the PC/developer interface causes a revolution in the way that people program.