I think of the iPad as a kind of dumb terminal. An end-user device with limited uses. I don't think it will bring an end to other devices. The primary reason being that you have to create apps on something. Also, I see this as something confined to the Apple universe - while it is a bright universe, and sometimes blinds us to the other Microsoft/Linux etc. universes, it's neither the largest, nor the only area for us developers to work and play in.