Shooting at the pelvic girdle is a tool in the arsenal. I'm not aware of any reputable trainer teaching that the pelvic girdle shot should be taken in preference to a COM shot, just that it's an option that one should be aware of.
The late Jim Cirillo wrote of this as a valid option/alternative to starting with the COM based on his and his unit's experiences with it. It was particularly well suited he stated for an LEO holding someone at gun point since you are able to see the suspects hands when focused on the pelvic region and cannot readily do so when focusing on COM. As we know, hands kill.
In his book he did not say write off the COM but that he saw the benefit of the pelvic shot first.
Has it replaced COM across the board, no. At least not for civilians. Guys who present themselves as Special Forces may say different and are in an entirely different environment if they are. If your two shots to the COM fail though you are going to need to switch to a higher or lower target. The pelvis may not be as reliable an area to rapidly stop someone compared to the head but it sure is an easier target to hit.