I was having a conversation with SWMBO about life after 10A. Her response is that while the PC(USA) slowly abandons the teaching about not conforming to the world, she's going to continue to preach about Christ, His death and resurrection to redeem us, and His teaching to Go and sin no more.
That said, if our state decided to OK same-sex weddings, she'd give up any right to certify civil weddings. She'd only do Christian marriage, which is defined in the PC(USA)'s Constitution part II (Book of Order) as between a man and a woman. If someone wanted to get married, they'd have to go to a Justice of the Peace, Court Judge or County Clerk for the civil registration and certificate after the Church Wedding.
As a flight of fancy, I extrapolated that further. It appears that a Christian marriage, joining a man and woman in Holy Matrimony is actually a good thing for those seniors who are living together outside of civil marriage because they would lose benefits if they were wedded in the eyes of the state. In this way, they could have all the blessings of a Christian marriage and not live in sin, yet to the state they are still the widow and widower of a previous spouse.
It is this living in sin that some one supporting Amendment 10A referred to when talking about the replacement of the fidelity and chastity language. Using my idea, there's no need to repeal 10A for this elder, just do a Christian Marriage. The elder would then be living in the fidelity of Christian marriage, which is not recognized by the state, but is recognized by the Church.
However, there is a sense that the next target of the LGBT alliance funded by the Arcus Foundation (see the Reformed Pastor's posts here and here) will be the area in the PC(USA) Book of Order governing marriage. Currently it says that Christian marriage is between a man and a woman, which according to some is non-affirming, and old fashioned. It should be interesting at the next GA.
And so it goes .....