The 9mm never needed the 2nd pin in the locking block. That was added when the .40 S&W was introduced, after they had some failures. IIRC, they continued to make the 9mm guns with a single pin for awhile. The Glock 20 (10mm) and 21 (.45acp) both came out in 1990 and both have 2-pin locking blocks. I suspect that while the 10mm has a lower model number, they were designed and developed at the same time and because of the 10mm, they used a stronger, common locking block. Following that logic, if Glock was trying to standardize the Gen5 with a single pin, then it might work with the .45 due to the lower pressure. My gut says that there isn't a large enough market in 10mm and .45 to make it worthwhile.
The Glock 21 and 30 are different in the same way as the Glock 17 and 19. The Gen 5 Glocks standardized on a Glock 19 locking block and modified the longer slides to fit what are essentially long and extra long G19 barrels. If there was enough .45acp market, I could see them doing it. But my gut says there isn't enough there to justify it, considering they invested in Gen4 molds and tooling. But I've been wrong before, so good luck!