We already knew the next game from inXile Entertainment wouldn't be a new Wasteland but now they hinted at the genre without explicitly saying what it is.
Microsoft recently posted one of those GIFs that can serve as game generators for your list of what to play in case you're indecisive. It can provide a gamer with the genre, platform and more clues about their next game, such as multiplayer or singleplayer.
While fans were listing their results, inXile's Twitter account popped in to say they rolled " NEW+FPS+RPG ". The devs didn't reveal much info about what they're working on thus far but these types of teasers are certainly on-brand for them and Microsoft as a whole. It is them that came up with Melissa McGamepass that "leaks" teasers for upcoming games.
Therefore, it's possible we will see this persona revealing more about inXile's next game through another spoof email soon but considering we are about a month away from E3 2021, there is a chance we are going to see a teaser in video form since Microsoft.
On the other hand, their presentation will be loaded with big announcements since there are several highly anticipated games in development already, such as Forza Horizon 5, Age of Empires IV, Starfield and Halo Infinite.
These big four have been in development for some time so they might be the main attraction with gameplay videos and deep dives so it's still possible inXile might still squeeze the RPG FPS project in with a teaser.