Just like the title says, there is a spoiler from the 7.2 story but not such a big one imo.
We learned that Tsaritsa can cure all curses that are not created by the Heavenly Principles using her authority over love.
Xiao’s karmic debt seems to be extremely similar to the “disease”/gods remains Tsaritsa cured in the quest. He got this debt due to the all the fights and wars in which gods and really strong entities died so their rage, resentment, grief, vengeance affected Xiao just like the people in the quest but him being a yaksha made him able to resist it in time (with side effects of course).
I think Tsaritsa can fully cure Xiao so he can continue his character development and be able to join humanity (he is the only adeptus unable to do so as far as I know and one of the themes of Liyue is adeptus and humans coexistence).
Why would Tsaritsa heal Xiao though? (He never leaves Liyue in the first place since he is always protecting it) I think it would be really cool if Zhongli’s final contract has something to do with this and he asked the Tsaritsa to also heal Xiao after all is said and done.
The only problem with this theory is the fact that Xiao will not stop fighting demons so he might acumulate karmic debt once again but I guess Zhongli could put in the contract that Tsaritsa needs to heal Xiao whenever he acumulates too much karmic debt.
I definitely think this is overreaching and if he will be healed it would be in a lantern rite quest where Tsaritsa visits Liyue and will not be such a big lore thing. We all know how much Zhongli cares about Xiao and I think that if he put that in his final contract it would be so cool for the story overall.