We certainly don't want to adopt UA's stupid boarding method - how many Silvers and Golds want to lose your EA boarding benefits during general boarding? Raise your hands. Hmmm...I don't see any hands
It really should be quite simple - figure out a reasonable cutoff for the number of Elites on a flight in Y where boarding should be done by status vs. normal. If the number of elites in Y exceeds this number, board by status, if not, use the normal EA boarding process.
It's really not that complicated.