I agree with this Sasuke will only be able to do it with a vulture kill. However, I don't think that it will happen because I believe talk no jutsu will be needed on Obito to get him to help fend off Madara. No one currently alive can stand up to the current OP Madara. Even with reinforcements Rinnegon abilities can just field wipe and without tsukage there isn't a lot that can be done against it other then Naruto doing some super tailed beast bomb. Honestly if this wasn't a manga where the good guy has to win Madara could have just killed everyone immediately, remember he has infinite chakra and can spam abilities like perfect susano and such. Sasuke might be able to use perfect susano soon, but would never be able to have the broken stamina or regen like Madara. As far as Minato beating Obito that was purely due to speed and lack of experience on Obito's part. Therefore I think Naruto will have to be faster to just hit him. I don't think without an upgrade Sasuke has anywhere near that speed yet. Another point is that Obito only has one sharingon so he can't use izanagi like he did with konan, so if Sasuke can pull something out that is sustained or maybe Kirin, maybe he would have a better way of dealing damage. Note that Kirin is traveling at the speed of light so I don't believe that it will be possible for Obito to phase shift away in time. Lots of possibilities so it's really up to kishi.