Other posters have pointed out that millions will be unemployed. That is likely what will happen unless we move out of our current paradigm of wealth-hoarding by the owners of capital. If this pattern continues indefinitely, all of the wealth on the planet will be concentrated into the hands of the few. The rest of us--including every last slashdot user--will be subject to their whim, at least until the machines take over.

Novelist & guerrilla ontologist Robert Anton Wilson has suggested that employees who design themselves out of their jobs be rewarded with a substantial portion of the labor saved by their innovation. He calls this concept R.I.C.H.: Rising Income through Cybernetic Homeostasis. This won't fend off the Machine Overlord problem, but will motivate workers to exercise their creativity, something that will have many positive yet un-quantifiable side effects.