hi DogeatDog,
I am in a very similar situation as you and my understanding is that as long as the Green Card is valid you dont have to worry about that. 319b is forward looking so their concern is whether you will continue to live together abroad after she attains her citizenship and whether you will return to the US in the future. Your only concern re the green card should be if it is still going to be valid for the duration of this process (if you have 1-2 years of validity left it should be fine). In my experience, the best bet for success is (1) applying online, (2) applying through an office that has a high success rate with 319b (so you may want to search all the posts). Message me privately and I can share more.
