Computers in general have helped cut down the use of paper in office environments. I think Tablet computers will help this trend even more. But it's a big call to say that it will ever replace paper completely.
For example, in my office I don't even have a connection to a printer. Never needed it!
For taking notes however (meetings, training, etc.), I am still waiting for the "real thing", not gimmicks. In the meantime I'll stick to my legal pad.