I'd certainly hope not. With ~30 states still allowing employers to fire employees for being LGB and 40+ states allowing employers to fire employees for being transgender, it wouldn't be time to stop.

A few orgs that focus solely on marriage would, but there's not many of those. Most orgs have broader mission statements than one issue. After all, we are a diverse community... Most orgs realize that but focus solely for results.

(1) Employment non-discrimination.
(2) Adoption by same-sex couples.
(3) D.A.D.T.
(4) HIV/AIDS issues, and how these issues impact the GLBT communities and populations (and even some that don't identify with "GLBT" such as "MSM's/DL's").
(5) Many other GLBT health issues, including do GLBT folks get equally good health care as non-GLBT's in all areas of the country.
(6) Electing GLBT candidates to public office.
(7) Many international GLBT issues, including young men and women being executed for being or identifying themselves as GLBT.
(8) If, God forbid, future science can someday identify GLBT individuals in the womb, that will open up a whole new can of worms that we can barely even think clearly on right now.

I'm sure I've overlooked some.

Probably all of us alive today will be six feet under before we can, properly, think about packing up the bookkeeping records and closing shop. But what we do accomplish is our legacy to the generations that follow us.