@Joel_Joestar as sweet as that could be, it's imposible. Miya's soul is now Sakuya, she wasn't possesed by Miya she was Miya, losing her attachments just mean she forgot her previous life to live completely her new one, not that Miya's soul left her body since it would leave the body with no soul at all if Sakuya is still alive, the cat can't be the og Miya
@Rialtoir
I think it's indeed a valid theory that reincarnation in this manga works in a way that the soul occupies a newborn body until it's finished with its business in the world.
Miya's business is finished, so her soul is released (possibly reborn as a new cat) and only the "true" Sakuya remains. Should Sakuya come into the situation that she dies with lingering ties herself one day, the cycle would begin anew.
As much as Hinata is a granny (Toyo) at heart, she's still very childlike, characteristics of the "true" Hinata.