Board Thread:Episode Discussions/@comment-25319479-20170531105724/@comment-24824859-20170605234713

The Wikia Editor wrote: To be fair, the entire situation with the dark chakra beast will probably be resolved within the current arc and there wouldn't really be much reason to bring it up afterwards.

As for Gaiden, most of the next generation characters within that story only appear for a single page if even that, Boruto himself barely appears in it.

We still don't really what became of Denki, Iwabe and Sumire later on, their absence in the manga might even be deliberate in order to keep their current status a bit more ambiguous, but that's just me speculating.

Iwabe, for example, might undergo some character development later on, deciding to deliberately not participate in the Chunin Exams because he doesn't want to rush things, instead deciding to train for the next Chunin Exams. No offense, but these all sound like excuses. Most of the new gen kids still appeared in Gaiden, so there's no reason why Sumire, Iwabe, and Denki didn't appear other than the fact that they're filler characters