Oh lord, here he goes again.
Hey, believe what you want. I think a lot of people are setting themselves up for disappointment.
On further consideration, I'm grudgingly willing to at least consider
Devin Faraci's theory regarding Inhumans on SHIELD, which is essentially that the most explicitly Inhumans-related elements will be kept as vague as possible and will begin and end, at least for the foreseeable future, in the next two episodes, being used more as a means to shake up the show's status quo (giving Skye and/or Raina powers?) than anything else.
But a bigger, longer, serialized Inhumans arc? No, I see no way that could happen unless Studios proper is willing to give the show a lot of latitude to define everything about the Inhumans not directly related to Attilan or the Royal Family characters. You can't have a serialized mystery unless there's actually shit you're allowed to reveal.
On a related note: what are people expecting to see Inhumans-wise in the films before 2018, given Feige's "sooner than you think" comment last month? Even if you assume he lied (or at least used very deceptive language) about Quicksilver and the Scarlet Witch being Inhumans, AoU has so much going on that I don't see how there's much room to do more than vaguely allude to their powers having alien origins. There's certainly no room for Inhumans elements in Ant-Man or Civil War, and Dr. Strange doesn't seem much more plausible. When we get into 2017, GotG2 and maaaaaaaaaybe Black Panther could have more setup, but the former isn't set on Earth and the latter already has its hands full introducing another fantastical city on Earth.
So, I could be totally wrong, but I'm skeptical that we'll get much more than foreshadowing and Easter eggs before 2018. There just doesn't seem to be much room for it in their slate before then.