About how  long will my touchscreen last before it starts to lose sensitivity? I've read on various posts on the net that touchscreens lose sensitivity over time, but I have not found any detailed information about why and how I can prevent this. Does anybody know why and how this happens, and how long it takes?
I have a T-Mobile G1 (the first Android phone) that's a few years old now and sensitivity on the touch screen is still intact.

If you don't treat your phone well it is likely that over time you're going to damage it or the screen can get so dirty that sensitivity might decrease, but it is not an issue with the touch screen technology. Any phone that is badly treated will get damaged.