I still shoot production and single stack because 3-5 mag changes in a stage, leaving a trove of magazines behind me in the dirt, dropping lower in the combined club match scores from losing extra time on a stage does not bother me at all.
But I am old and don't care, just happy to get out and run and play with guns still.
I think 15 round production would bring a few of the shooters who actually do care about all those things back to the division, but not troves of them.
It won't change the dynamic of this sport being very much optic dominated at the club level.