Next chapter, Sasuke poofs into smoke and turns into a log.
Substitution jutsu can't be detected with teh Sharingan.
That's what Hashirama taught him, the single most OP'D jutsu.
Sasuke won't get a new Power, he just got some of Hashirama's Chakra that came with a Jutsu to counter Madara. That is all.
It's not like he's getting Rennigan or anything. :l
Wouldn't surprise me. Sasuke may not have TBB boom explosion attacks but he's a very skilful ninja and him pulling off a Substitution [which he can use effectively] against an opponent like Madara is plausible imo.
Wouldn't be too mad simply for the fact that Sasuke has been shown to use the technique now and again.