The overture will be voted on at Presbytery meetings. If a majority of the Presbyteries approve it, the Book of Order will be changed, and the Presbyterian Church (USA) will be history.
A very similar proposal came before the regional Presbyteries several years ago—I’m thinking around 2005 or 2006—and failed to be ratified by a majority.
Still wondering—50% or 2/3 majority of Presbyteries?
50% or 2/3 vote to pass within each Presbytery?
It really should not matter, because Genesis 2/Matthew 19 should not be subjected to a vote.