All well and good to try to pretend this will have no significant impact. I'm fairly certain one of my usual flights had 18 platinums out of approximately 160 seats, on one occasion. Based in status qualification ratios alone, without considering that is a popular flight for frequent flyers, suggests 36 golds. So a 200% increase in PB lane usage. Just a few people. Nothing really.
Given the allocated domestic boarding is 20 minutes, those figures average out to 2.7 pax per minute using the PB line (up from the 18 odd you specified and not including those seated in J - averaging around 1 pax per minute). Maybe a 200% increase but still an insignificant amount in the scheme of things.