I strongly suspect that the Prayer Beads contain Worlds and they are designed to have the “Kinzo” of them die a short time before Rika dies.
After that it’s a race to prevent “Beatrice” from detonating the World inside the Bead. All attempts have failed and the Human Parts of Rika’s Soul get shoved into the Rika of the World the Prayer Beads are in.
Rika is the Natsuhi which explains why Kururu seems to have a particular grudge against her but what will happen if she finds out that Rika has no memories? She will realize the true nature of what’s going on and seek out Lambdadelta I.E. the Gamemaster whom I’m certain is the Eva of the World inside the Prayer Beads and the Game Piece of Eua I.E. the true “Virgilia” who can survive her Kumasawa form’s demise(Kumasawa is just a sword after all).
Originally she made every effort to taunt Rika inside Hanyuu before using “Beatrice” to detonate Hanyuu’s horn(and later Lambdadelta’s horn after Hanyuu recklessly killed herself using her Featherine Augustus Aurora/“Kyrie Ushiromiya” persona wielding the broken remains of Kumasawa in order to Loop after Rika got hit by a truck) causing the crack we all know about.
Lambdadelta the Gamemaster pretends to care about Hanyuu yet desires to kill her with absolute certainty and do the same to Rika.
Bernkastel is made from the inhuman parts of Rika used to create “Kinzo” I.E. MIYAO Mitake.
Incidentally characters from Ciconia seem to find their way into the Higurashi Rei(wa) World suggesting that some denizens of the Prayer Beads figured out what is going on due to just how much time they inhabited the Prayer Bead compared to the other Gameboards of Lambdadelta.
Inori Mikazuki seems to act like Hanyuu in the first few Loops yet in the small amount of time we’ve seen in the final Loop she seems to act like Rika. If Rika is Inori in the final Arc then she will give herself away to Rika herself giving Rika a clue to what is going on with Looping.
Will Inori arrange for Kururu to meet Rika just to make sure both realize the truth maybe? Will Sakiko expose herself as Lambdadelta revealing her Hanyuu form before getting threatened by Satoko(who clearly doesn’t trust her Husband at least and doesn’t object to anyone suspecting the Kimiyoshi Family which should include Sakiko) in an ambush only for her to kill Satoko with the Hinamizawa Syndrome and Loop her into the Sakiko Body only to get shot abruptly right before Kururu sends a Stake of Purgatory(which when sent by Kururu into Lambdadelta’s body would be no different from Kururu going in herself) to detonate Lambdadelta’s Horn in Lambdadelta’s face killing her?
In that case Hanyuu(the true Featherine Augustus Aurora the true “Ange Ushiromiya” and true “Maria Ushiromiya”) will probably get in contact with Kisaku(whom I’m certain is the real “Rudolf Ushiromiya”) and Kisaku will hunt down the “George Ushiromiya” of the Hinamizawa side while Kururu contacts her “father” the “George Ushiromiya” of the Polaris side.
Kururu will upon realizing Kururu took down Lambdadelta will fly into a rage and begin plans to eliminate her that would be cut short due to the Holy Mother of Polaris Featherine Augustus Aurora(actually the true “Kyrie Ushiromiya”) using her Ikuko Hachijo powers to eliminate him the same way she did with Lambdadelta once and send Bernkastel to fetch the remnants of Lambdadelta so that she can move to the next game.
Kisaku upon reaching the “George Ushiromiya” of Hinamizawa’s side will kill him then shoot an enraged Eua in a mutual kill that will cause the denizens including her mind’s deity(who honestly has no need for Eua to outlive this epic finale) to flee completely shattering her horn completely leaving behind a dead little girl with a bullet in her head.
Any investigators will have no idea who the girl is nor will the villagers or Polaris making Kisaku’s motive unknown to a few besides Rika, Satoko, Inori, Kururu, Keitarou and Hanyuu and his means of death an even bigger mystery even if the body of Lambdadelta is found next to Satoko’s old body with Hanyuu identifying Eua’s corpse as the true form of the Demon plaguing Hinamizawa mimicking the form of Oyashiro Sama.
Since Rika is the High Priestess and corroborates Hanyuu’s claim of being Oyashiro Sama and of Lambdadelta being the avatar of a Witch attacking Hinamizawa to take advantage of the legend of Oyashiro Sama the village will have no choice but to accept the explanation with Polaris being horrified that the rich greedy Aunt “Eva” was an avatar of the true culprit behind their world’s destruction all along.