ICICLE - the Icicle's son was one of the main villains during the last but one run of the Justice Society so it wouldn't surprise me to see either the original or the son return in the pages of Earth-2 before the end of the year. Chalk him up as a possible.
THE INFERIOR FIVE - unless these guys make another played for laughs appearance in an anthology title like they did in 2010's The Brave and The Bold, I think it's safe to say we've seen the last of them, sadly.
INFINITE MAN - a Legion villain so I'm taking a complete guess here and erring on the side of not seeing him any time soon. Dave Sopko, the official COEP Legion go to guy, agrees saying "Really doubtful that he will be seen for quite a while."
INFINITY INC. - whether any of these guys turn up depends, I suppose, on what Robinson does with Earth-2. Even though the solicitation for the first issue came out last week (it's 20th Feb as I write this) there wasn't a whole lot to go on. So while I think we may see some of the characters (and I'll deal with them in their own entries) before the end of the year, I don't think we'll see them officially teamed up as Infinity, Inc.
INFINITY INC. HEADQUARTERS - see above.
INJUSTICE GANG OF THE WORLD - while I'll deal with the individual characters in their own entries, I do think it worth pointing out that this is the bunch Libra set up. You remember Libra, don't you? The big bad prophet of Darkseid in Final Crisis? Yeah, we won't be seeing him again.
INJUSTICE SOCIETY OF THE WORLD - while I wouldn't swear to it or make any guesses as to its membership, it wouldn't surprise me if James Robinson had some version of this turn up in the first arc of Earth-2; bearing in mind there'll only be six or seven issues before the end of 2012 and I'll put them in the possible list.
THE INVISIBLE DESTROYER - another of the old Green Lantern villains that Geoff Johns could probably update and make interesting but with everything he's got on his plate at the moment, I'm going with a no.
INVISIBLE KID - another Legionnaire so I'm a little in the dark here. I think one version of him has shown up in the new Legion series but I can't see to confirm it right now so I'll put him in the possibles. Dave Sopko clarifies, though: "Invisible Kid I - Still dead. So no appearances outside of a flashback story. Invisible Kid II - Active in the Legion of Super Heroes." So he comes out of the possibles and into the in place column.
I.Q. - I don;t think Ira Quimby's appeared yet but am pretty sure he was name checked in Justice League so it wouldn't be at all surprising to find him appearing there pre-villainous career. I'll put him down as a possible.
IRON MAJOR - DC might be going for war titles these days but war titles starring Nazi majors with metal hands? I'm guessing not.
So in summary, one in place (Invisible Kid and the surprising I... Vampire), no definite predictions and three possibles (Icicle, Injustice Society and I.Q.)