Things have not been looking good for #Inhumans for quite some time. Set photos and the first official image weren't at all well-received, while the trailers for the series pointed to the ABC/IMAX collaboration not being anywhere near as good as all that talk of a big budget suggested. In terms of box office performance, Inhumans did only ok earlier this month and ratings are expected to be low.
As a result, it probably won't surprise you to learn that ABC and Marvel seem to be preparing for the worst. According to Renew Cancel TV, the network is promoting Inhumans as "the COMPLETE series" rather than a first season and that's led them to believe plans for a second season have been scrapped.
Nothing is set in stone, of course, and it's entirely possible that a second season could happen if Inhumans exceeds expectations when it debuts later this month. That's probably quite unlikely, though, especially as word of mouth isn't good and viewers are unlikely to tune in as a result. It's a shame this has happened but at least the door is now potentially open to the property being rebooted as a movie
That's likely a long way off, unfortunately, so for the time being, we'll just have to put up with this iteration