No reboot; serious advancement.
At the end of #3 the Architect agrees to shut down the matrix and release humanity, this however was a backhanded poison pill: the earth is too decimated to support more than a handful of humanity outside of their incubators, additionally (as was said in the first movie) a vast majority of those living in the matrix are too dependent on its system to psychologically survive once disconnected. The end result is mass death as Zion collapses under the burden of supporting the millions of starving, psychologically dysfunctional liberated humans. On top of which, the entire bit about humans as a biological energy source was total horse shit; the Machines real bio-generators are actually well hidden away, and run on any number of herbivores (possibly cultured whales).
It was a lie from the Machines about the true purpose of the matrix: cloud processing.