The being said, the one thing I’m curious about is what is the irreparable damage Sailor Chaos did that would make Sailor Cosmos want to convince her past self to destroy the Galaxy Cauldron since it essentially guarantees she and her loved ones will be immortal?
I thought of something when I watched the new scene of Sailor Cosmos' defeat. We see that Sailor Chaos has destroyed the Crystal Palace, and it is atop its ruins that Sailor Cosmos gives up. We know the Crystal Palace is made of the Silver Crystal, and the Silver Crystal is analogue to Usagi's heart, meaning that this future version of her gets her literal heart destroyed... so she gives up because without it, she can no longer protect anyone.
It's a very poetic and vague idea, but I think it fits the poetic and vague character of the storyline. At any rate, it makes me curious just how the Crystal Palace could be destroyed to begin with, that thing withstood several, huge Black Moon and Nemesis direct attacks.
For some reason, I always imagined the Cauldron to be an atemporal location, but its future destruction would also make sense.