I’ve experienced BSA as a cub scout, as a teen-aged explorer scout, and as a scout leader when my own sons were scouts. My daughter would have loved to be able to participate - she did girl scouts but was much more interested in camping and backpacking than my sons ever were.
Also, the vast majority of experiences available to boy scouts are driven by local leadership who make use of materials provided by the national organization but tailor the activities to their particular group of scouts.
In my opinion girls who are interested will only enhance the BSA experience, and the loss of opportunity for ‘boys only’ time might actually be more positive than negative. As long as enough mothers participate in leadership there will always be opportunities for occasional break-outs by gender if deemed important to the local group.
Perhaps organizational naming needs to evolve to BGSA. Then keep cub scouts but come up with some gender-neutral qualifier like ‘adventure scouts’ for older-than-cub scouts. (I know that’s similar to already taken venturing, so maybe there’s a better alternative.)