For me, this image could mean several things.
It could be a simple nod to our original Ineffable Husbands.
Or it could be another universe where they are once again an angel and a demon, but a new version, but with a happy end this time.
Or it could be another universe where they are simply the universe of the book Good Omens, with their lives continuing positively after the end (without seasons 2 and 3).
Or it could be another universe where our Ineffable Husbands made different choices (whether for the end of season 2 or season 3).
Or it could imply that one day our Ineffable Husbands will become themselves again with all their memories (of all the different universes).
And for me, all the universes we see could mean either that:
Firstly, God created all these universes at the same time and placed the souls of our Ineffable Husbands within them so she could see them evolve in different ways many times, because she couldn't imagine a universe without them (they must have entertained her immensely). And yes, even if all the universes were simultaneous, it would still be them each time. Firstly, because we know it's them thanks to the writers, because it's their love that endures in all its forms. But also because I don't know if you're familiar with the theory of alternate universes where there are other versions of you, but it implies you would inevitably be connected to them because it's still you, still your soul, but with different choices and context in other universes.
Or, secondly, God did indeed create a single new universe, but we see at the end all the other universes she will create, one after the other, each time the old one fades away. We see them all at the same time so that we, the viewers, can see what God has ultimately done/continues to do, and above all, how the love of our Ineffable Husbands will always endure, regardless of the new world that will eventually emerge. But also because we would simply be seeing the end from God's perspective. God, who is beyond time, knows everything about her own creation—past, present, and future. So instead of seeing a single universe with the others erased, we see them all at once, like she probably do, because time for her not really exist.