While it doesn't follow to say that touchscreens will eliminate hover states, it is factual that touchscreens cannot accept hover states--you're either touching the screen or not.  In the future, there may be a technology where hovering your finger over the screen could translate into a system action like hovering a mouse.  Until then, if you're designing something for a touchscreen, it's best to not design critical user interaction around the hover state.

Although there are not hover states yet, you can check what 37signals made for their iPad Basecamp app

productblog.37signals.com

I think the "hover states" won't disappear as I don't think all devices will have “touchscreen and touchscreen-only” input methods.