So now we know that Lobo's release will not only see a compatibility pack, put it will also coincide with the release of two paid skin packs (Teen Titans and Bad Girls).
If one assumes that the trend of two costume packs being released along side a character remains true for the remaining three characters, that would mean 6 more skin packs (plus one skin for each of the compatibility packs, so 21 skins total).
However, the Preorder Skin Packs will probably take some of those slots. For the sake of argument, let's assume it breaks down like this:
Lobo: Teen Titans Pack & Bad Girls Pack + Flashpoint Batman Compatibility Skin
Batgirl: Arkham City Pack & [New Skins] Pack + New Compatibility Skin
Character #3: Red Son Pack & [New Skins] Pack + New Compatibility Skin
Character #4: New 52 Pack & [New Skins] Pack + New Compatibility Skin
(Side Note: Assuming the price of the Flashpoint Pack is consistent, then if you don't have any of the above, the total cost of buying the skins listed there would be $32...then add in the $15 Season Pass to reach $47 total for all DLC).
Then throw in the Blackest Night and Arrow skin in there somewhere since they aren't convenient packs of 3 skins like all the others. No idea how they'd price them though.
That leaves us with at least 12 new skins that we don't already know about (9 from unknown packs and 3 freebies for compatibility).
However, let's do some quick math.
24 Characters with their Default Costumes
+24 Alternate Regime/Insurgency Costumes
+27 Preorder/Unlockable Costumes
+4 DLC Characters (for the moment we're assuming they're not getting alternates)
+4 Compatibility Skins (Flashpoint Batman + 3 Unknowns)
+6 skins from the Teen Titans Pack & Bad Girls Pack being released when Lobo is released
+9 skins from three different Unknown Skin Packs
=98 Skins Total
If DLC Characters have alternate costumes, that brings us to 102, which meets Boon's quote of "Over 100 skins." Which again means that there are only about a dozen skins that we haven't already seen (not counting DLC characters). If DLC Characters don't have alternate costumes that means there'd need to be at least another skin pack to bring the total to 101 (which also meets the "Over 100 skins" quote).
Granted, I've learned to expect the bare minimum from game developers, as if I don't get my hopes up I can't be disappointed. Especially after all they could have done for MK but they only did retro alts for ninjas and cyborgs. So for the time being I'm only expecting there to be about 12 or so skins left to be revealed for this game. Which is still a lot more than most games. If there are more, I get to be pleasantly surprised.
(Naturally this all goes out the window if they decide to do a second season pass)