Marvel Television and Fox Television have been working together to get multiple X-Men TV series off the ground. Hellfire failed to launch but was replaced with another X-Men TV project in development. Most exciting of all though is Legion, the FX series which is set to premiere in 2017. The first trailer for the series launched at Comic-Con International: San Diego 2016.
The exact status of how Legion fits into the ill-defined continuity of the X-Men cinematic universe has been a matter of some debate. At times it has sounded like the series will exist right alongside the X-Men movies, and at other times it sounds like it takes place in an alternate timeline, thereby avoiding having to deal with any pre-existing continuity.
What no one expected was for Legion to be a part of the Marvel Cinematic Universe, but an article on Marvel.com suggests that may be the case. The article is a rundown of all of the new characters coming to the "MCU" that made a splash at Comic-Con, and Legion is right there on the list, alongside MCU heavies like Captain Marvel and Luke Cage.
Now, we should keep in mind that the article was written by someone who works for Marvel.com, and is not written by or quoting someone with any actual power to make those decisions. In other words, this could just be a typo or an oversight. On the other hand, Marvel Chief Creative Officer Joe Quesada did pitch the Legion trailer as a "brand new Marvel show." Scott Derrickson, the director of Doctor Strange, did also say that Doctor Strange will begin the "Marvel Cinematic Multiverse," which could perhaps redefine what we think of as the MCU.
While we hope this turns out to be true, we're going to take it with a grain of salt until we hear it from the lips of Quesada, Kevin Feige, Noah Hawley, or someone else with some real pull at Marvel or Fox. In the meantime, you know what they say: "It's all connected."