Not change so much, but if 'touch' refers to some sort of localized haptic feedback mechanism (eg you can close your eyes and feel the position of individual icons/controls as if the screen were slightly bumpy) then it will cement the iPad's dominance as a musical performance tool. Imagine, for example, being able to strum a virtual guitar and feel approximately where the strings are, rather than receiving different messages from your fingers and your eyes. It doesn't have to be perfect, just suggestive and consistent, which will provide enough novelty to keep people busy until the iPad 4 appears :-)

I have a strong hunch that that Apple has stolen a march on the competition here. When I first picked up an iPad, one thing I looked at was some sort of space shooter game (Galaxy on Fire or something). I played for 2 or 3 minutes, and was impressed by both the graphics and the vibration every time my ship took a hit, like the controller for a videogame console. Later I got an Android Honeycomb tablet, and one day I noticed the same game was available, so I installed it. Everything was fine, except that there was no vibration. It seems that since large tablets are not phones, few, if any, manufacturers saw a need to include a vibration feature and so Apple has had several years to develop both the technology and a coherent set of UI conventions to employ it.

I know virtually nothing about haptic technology, but I have a guess about how it might work. Imagine two vibrating motors at right angles to each other, whose periods are fixed and proportional to the ratio of the device's width:height. Now imagine a second motor for each of the pair, which vibrates at up to double the speed of the first; by varying the speed of the second motor in each of 2 dimensions, interference patterns are created in similar fashion to the beating that occurs between two sine waves of different frequencies. Where the periods of sinusoidal sound waves stand in neat integer relationships to each other, you get the familiar notes of the musical scale (warning: drastic oversimplification of musical tuning theory). I speculate that people are so intuitively used to this - sound being just a more sensitive version of touch - that it may allow a tactile illusion of up to 12 identifiable 'zones' in each screen dimension, resulting in a grid of up to 144 'touxels'.

If I turn out to be more than half-right about this, then I feel it ought to be worth some sort of nominally compensated blue-sky consulting gig :-)

EDIT: of course you could go on and on with the other applications. A lightweight keyboard for blind people, new models of games interaction, interactive multidimensional graphing/modelling tools where constraints are proxied by 'resistance' and so on.