Being in a venturing crew myself, I really don't see a difference with this happening. I feel it will get more members involved especially when both your sister and brother/ son and daughter can now go to the same events.
I've worked multiple summer camps before too and it was not uncommon to see both girl scouts and boy scouts attending. Though due to the different schedules it would become tedious to work between two different sets of kids.
Though as it is was with boy scouts and adults, it will be quite strict when it comes to separation for things like sleeping quarters and restrooms as it always has.
Ultimately having everyone do the same thing will save move for the BSA and allow for more members and income as is. I've seen first hand too that places aren't doing too well money wise so this will be a welcome change.
And as others have said, girl scouts (the organization) is really lower quality compared to what boy scouts do. Several of my female venturing crew members have explained how much more involved they get to be with venturing crew compared to in girl scouts alone.