They will (hopefully) get around to it -- they are just getting started with the MK IV, and there is already plenty of pent-up demand for the design. I'm waiting for a short, tapered barrel before I pounce as well. I remember a similar situation with the wait between the Glock 42 (.380) and Glock 43 (9mm) -- basically, in a situation with high pent-up demand, it's in their interest to release minor variations of what everyone has been waiting for, before releasing the definitive model. At least, that's the theory.
They clearly don't mind making weird machined barrel variations, so the classic design with a short, light barrel can't be too far out. The fact that the bull barrel version has "TARGET" emblazoned on the side in giant letters is another hint that it's not going to be the new standard.