I doubt it, at least not anytime in the near future. Stamps do have some interesting and necessary purposes for existence.
I write people in prisons. While some prisons and jails have e-mail systems in place through which you can write an inmate and, in some cases, the inmate can write back (Federal prisons being the best example of this) these are usually funded by a "tax" paid by the inmates in some way. For those inmates who don't want to use such services or cannot (California prisoners being one in that they don't have access to such systems), U.S. mail and stamped envelops are the only way to go. So, as long prisons don't have some other inexpensive way for inmates to communicate with those on the other side of the razor wire, stamps are here to stay.
Incidentally, because I write to prisoners I learn all sorts of things about life there. Since prisoners are not allowed to carry money, they use a barter system to buy and sell things. There are four kinds of currency in jails and prisons in the U.S: ramen noodle soups, instant coffee wrapped up in sandwich wrap, cigarettes (if they are permitted), and postage stamps. Think of the economic depression that would occur in the prison economy if stamps disappeared!