The best advantage of the Tablets is the battery back up and the portable size. But they wll not replace the Laptops considering the power of computation that is required by the laptop. But what we will see in future might be huge demand for the tablets coming from the different industries where we will have a necessity of a handheld computing equipments.
My feeling is that you ultimately want a do everything device that you can carry. Thus, a huge smartphone/mini tablet that has music and video, suitable for reading, internet access, camera, and communication. The current crop of superphones come close to meeting this. I suspect the iPad will become smaller and the iPhone will become bigger. I don't see laptops exiting any time soon. Perhaps they will make shirt pockets bigger!
I think the Netbook market will be hit really hard by Tablets. As for displays, for Tablets it already seems to be converging on 7" and 10", the "Big Phone" and the "Sofa Pad". Initially I thought that Tablets would be a niche market but I'm now coming to the conclusion we are seeing something radically new, especially given the software apps model. This is the new universal interface for just about everything, from TVs to Home Automation (at last).
It is really very tough to predict the acceptance of Tablets in place of Netbooks and Notebooks. It is also very tough for users to be only Tablet dependent, but yes if some brand comes with a combination of keyboard and touch screen with determined quality then that will surely supersede iPad.
It is not only a gambling for display manufacturers but it is same for touch screen and chipsets manufacturers.