sword art online 4

Hey, i just finished sao WoU, and I am, confused? What is going on with, spaceships?? I was waiting for a true kết thúc, explaining idk that underworld would be saved, that kirito and asuna would be able lớn connect lớn the underworld everytime they want lớn see alice and all their friends. I know it can seems naive but I even trusted the fact that it was a prank all along and everyone that died during alicization (eugeo...) had their fluctlights stored and could be restored... So my first reaction was lớn kiểm tra on mạng internet, what happens lớn the underworld in the light novel? But... no informations ? The next books are just a side story and then unital ring with the release of a new game, sánh the story goes on as if the underworld have never existed? Everyone forgot about it? Please guys I dont understand, what happens lớn Alice, lớn integrity knights? The underworld has turned into a cyberpunk world? Why are the apprentices of Kirito and Eugeo still alive after all these years? It means that everyone else still alive too in the underworld? And what will happen with the copy of kirito? We have seen the ghost of eugeo sánh many times, sánh will he return? I just need lớn understand the transition between WoU and Unital ring please...