You can't blame Gibson for fading out production of a model that doesn't sell in meaningful quantities over a period of what was it again, five years or so? That's not throwing things against the wall to see what sticks.
Gibson is a vintage brand and anybody buying a Gibson product doesn't primarily want the newest groundbreaking, hot shot model of a bass, but a piece of history. And that history is for better or worse defined by the TBird and the SG type basses which overshadow anything else, the two models covering qite a bit of differentiated ground between them, a long scale and a short scale, a neck-thru and a set neck. There might be a room for another model, but for some reason Les Paul shape basses (whether single or double cut, short or long scale) have never proved to be consistent sellers.
But is there really a short scale bass anywhere that sells better than the SG shape basses by Gibson and Epiphone? And likewise a bass with a "strange" (angular and non-symmetric) shape like the TBird that has sold better during the last 35 years?