Highly unlikely, as OS X has always been used to differentiate between Mac OS (Which already exist) and Mac OS X (Now branded OS X).There will never be an OS called OS X 10.12. Apple will morph the naming scheme to macOS… And why not? There's iOS, watchOS, and tvOS. macOS is the next logical step. The added benefit is that it removes numbering, which will get more confusing than it already is when iOS 10.0 is released.
My money is on "macOS Chavez Ravine."
It will be called, 'Mac OSX-let's-release-another-and-shorten-the-list-of-Macs-that-can-run-it.'