RTD is being disingenous. They've already started casting (for guest roles at any rate) for S4. The process of greenlighting is so convoluted and time-consuming, it's not as simple as yes, no, or still waiting for a decision. It can take a lot of time to go from, "yes definitely it will happen" to "yes and everything is signed, sealed and delivered" and usually things are not announced to the general public till long after everything is signed, sealed and delivered.