I know I'm going to get a lot of hate from Inhumans fans but I think it is an elephant in the room that needs to be addressed.
Many have said that the Inhumans need time to flourish so that they can become popular characters but from what I'm seeing they're failing in both the comics and on-screen.
Let's start with the comics. Out of all the Inhuman titles out there only one of them is selling above 20K an issue while the others all do below. That of course is Ms Marvel whose series isn't entirely about her being an Inhuman. The other series all about the Inhumans are low sellers, I was even surprised to see that Secret Warriors really took a nose dive in sales. They've even had a few other characters who had their own series like Mosaic and Kid Kaiju that were both laughably bad selling wise.
Going onto their onscreen presence. Their reception in Agents Of S.H.I.E.L.D haven't really gone down all that well and their own TV show that premiered in IMAX is being given the big thumbs down by critics and numerous fans. If it gets low ratings on TV (which I predict that it will) the series will be cancelled before a second season can be ordered.
From the information I am seeing I can't see how the Inhumans will be continued to be pushed when both readers and viewers are shying away from them.