We've sort of, kind of, known Appmon's length for quite awhile.
We've seen the number 52 pop up in a few places: DVD solicitations, MIPCOM, etc.
We have something slightly more solid now though (since solicitations or even licensing info could be incomplete.)
At Anime Japan 2017 a flier is saying the series will run for 52 episodes. (Anime Japan has numerous business components to it, so slightly more technical bits of information are sometimes expected.)
So we can solidly say this... Appmon as we know it is ending after 52 episodes.
As for what, if anything, continues on after those 52 episodes... that's still unknown.
Digimon as a franchise has historically changed names and concepts on a normal basis; so whether we get a 'series 2' of Appmon, an entirely new Digimon series, or nothing directly after Appmon is currently unknown.
Hopefully we receive an image of the flier soon so we can see if it has any further information or details to clarify.
Thanks to ANN for the news.