Athearn made an SDP40 years ago in HO. Financially, it has one big advantage over the SDP45, as it can use the SD40/SD45 chassis. In fact, it's relatively easy to kitbash one from Kato parts, starting with the SD45 frame and an SD40 shell.
That doesn't help Atlas much, but one can hope that Kato, or more likely an aftermarket shell maker, will try it someday.
The problems with the SDP45 are at least threefold. First, they were rare, though not as rare as the SDP40. Second, they came in two very distinct versions, so satisfying the three buyers' fans would require two different hood castings, not just detail changes. And, as noted above, they need an entirely new chassis.
What I'd like to see is an SDP40F, which was sold in much larger numbers and used across the US. But that also seems unlikely in the near future.
