Those Two

[Uzimaki Akira]

I have the feeling that Orochimaru is going to take Sasuke to one if his unknown hideouts and perform an Edo Tensei on the First and Second, this is why I believe this:
http://www.narutobase.net/manga/Naruto/118/3
In part one Orochimaru summons the two Hokage to fight the Third, but the point of this is to show that he has access to their DNA. He apparently is the only person to possess Nidaime's DNA and one of the few who can summon Shodaime.
It has been stated that they were in an alliance with Madara, who else would have intel on him? No one else faced him and survived save OOnoki and the two Hokage.
http://www.narutobase.net/manga/Naruto/399/12
http://www.narutobase.net/manga/Naruto/399/13
The Second was rumored to have kept a close watch on the Uchiha, how close is debatable but it begs the question, what secrets did he uncover?
If my assumptions are right (and forgive my arrogant tone but they usually are 9/10 times) then the best two, those two whom Orochimaru speaks of could very well be the First and Second Hokages, the only other intimate party to the nature of Madara was Izuna and I think it highly unlikely that we'll see him.
So what do you think? Could it be possible that "those two" are actually the first two Hokage's?
http://www.narutobase.net/manga/Naruto/593/11

[DexterMorgan909]

all the previous hokages were sealed, so they can't be used for edo tensei...period

[rikerslade]

They're sealed so they can't be revived.

[spade3dg]

Hey Orochimaru broke a "inescapable sealing" so its plausible.

Tobirama was a master or s/t ninjutsu so maybe he can find a way to escaoe. You never know.

[Sasuke eats nards]

all the previous hokages were sealed, so they can't be used for edo tensei...period

this!

[Uchiha Samater]

ill entertain this as one of many possible theories as who they will see.

Is'nt orochimaru's jutsu locked away in that seal also? (correct me if im wrong)

whose to say he was not obsessed in breaking that seal, maybe he has found a way.

[Uzimaki Akira]

You guys forget that Orochimaru's arms are no longer sealed so the jutsu can be broken by reviving new DNA.

[rikerslade]

Hey Orochimaru broke a "inescapable sealing" so its plausible.

Tobirama was a master or s/t ninjutsu so maybe he can find a way to escaoe. You never know.

They cannot come back. And it was never stated he mastered S/T, but had a S/T. For all we know, it's weak.