Itachi and Sasuke swapping eyes
I'm not sure if this is possible, but let's say Itachi told Sasuke the truth about his clan. Let's also say Sasuke understood why Itachi had to kill everybody and they decided to protect Konoha together.
Now, we all know Madara took his brother's eyes by force as it's pretty common sense that you can not die if someone takes your eyes surgically. Back then they didn't know about EMS, but in the current storyline they do.
So is it possible for the brothers to swap eyes and both gain EMS? The only problem I see in this is that Sasuke had a normal sharingan. However, Kakashi managed to awaken his mangekyo even though he is not an Uchiha so that makes me think:
1. Sasuke takes Itachi's MS eyes which obviously turn into EMS even though he didn't have MS himself because the eyes in a different host gain permanent light.
2. Itachi takes Sasuke's ordinary sharingan, but still manages to unlock EMS. Why? Because Itachi had already achieved the next step so his body somehow remembered it (kinda like Cell returning in his perfect form without C17 and C18), which leads to him getting EMS as well.
By doing that I believe both would awaken EMS and Itachi would regain his health. How? Well, Itachi said that Sasuke's eyes would grant him true immortality so I say that would mean cure him of his disease too.
Then they could return to Konoha. Before you say they're criminals, let's analize their status.
1. Sasuke is a missing-nin, but to that point of the story he didn't actually do anything bad at all. He would be able to return to Konoha because we all know the 5th has decided not to kill him until recent events.
2. Itachi's slaughter of the clan was his mission so technically he could also return to the Leaf. He didn't do anything wrong since joining Akatsuki and we all know he did it in order to keep an eye on them.
To wrap this up, Sasuke and Itachi would both get stronger, (maybe) be immortal and thus help Konoha and the Alliance in defeating Madara as well as restoring their clan.
So, what do you think?