There is a bit of a movement that resurfaces now and then in regards to dropping standardized tests. Some MBA programs such as Executive MBA waive the GMAT requirement for well-experienced candidates.
At the same time, the GRE is taken 900,000 times a year and is used quite widely. I can see that some of the less competitive programs may choose not to require the GRE in attempt to draw and entice more applicants (similar to how Online programs have done) to maximize applications and profits.
I think at the time being the most competitive programs have no reasons/drivers to exit the GRE.... welcome a rebuttal