The TOB Omnibus were release on Halloween, so there is still hope for a 2013 Horror Omni, if I were to make a guess the next volume will be either a long running series like
Werewolf by night, Ghost Rider or a duplication of the Marvel Horror 2 essentials, those 2 volume did collected a lots of 70s favorites.
And I think there is a lot more Interest for characters like Werewolf, Ghost Rider, Son of Satan, Living mummy, Morbius, Manwolf, and few others then yet 2 more anthologies of short 
horror stories like the Tower & Chamber, and they are not nearly as good as their Atlas era counterparts.