Peach, the only problem I have with your theory of what CBS means is that CBS itself has not announced a spring cycle renewal in a long time; its always been more indirect indicators during that time.
And the indicators aren't always there either, such as season 18 and 24 which were returning Racer seasons. And with 11, 18 and 24; that suggests we're about due for another returning racer type season for the spring.
Barring a major wave of terrorism everywhere TAR would normally be filmed for the spring, personally, I would expect a cycle 30. But that's JMHO. YMMV.
had to fix a typo, i.e., 18, not 28; and to fix that incoherent last sentence.