Orochimaru wants to observe. To witness.Op if he really wanted to edo tensho a powerful shonobi. Why didn't he just edo tensho Sasuke after killing him in his sleep at his hideout?
He is immortal, so whether he does something now or later does not really matter. In the end, both Sasuke and Naruto will be dead and Orochimaru will become an owner of their souls.
It's interesting how all the Uchiha you mentioned are like dead right now, while Orochimaru is climbing up the top ladder.I have lost count of the number of times Uchihas soloed this fodder