I'm not trying to validate the manga like some others. You can find an excuse or loophole for everything so it's certainly true that some efforts turned pointless and he's winging a lot of it. But I'll be danged if Orochi's gonna wind up surviving the couple years until he can take Sasuke's body. Even THIS manga isn't going to last THAT long/ Bust out the last rites and kiss his slivering arse goodbye.