Epic Games have been working on the a Machine Pistol since the Fortnite X Marvel crossover in Chapter 2 Season 4. We first saw the concept as it related to Mystique. Many fans assumed it would be her Mythic weapon for the season.
Season 4 ended with no Machine Pistol, but Epic accidentally added it to an LTM for a day or two before removing it.
Now, four seasons later, Epic pulled the same move as the Machine Pistol still hasn't seen the light of day in the base game. They accidentally added it to the Unvaulted LTM, and are still available at the time of writing.
Epic Games has once again included the unreleased Machine Pistol in an LTM, it can currently be found in the Unvaulted LTM pic.twitter.com/bxJfIeIlPv— iFireMonkey (@iFireMonkey) October 8, 2021
Does this mean the Machine Pistol will be here soon? We have no way of knowing, as this already happened and we still haven't seen them in normal Fortnite.
We could see this weapon in Season 8, or 9, or never. It's interesting to learn that Epic are still working on the weapon four seasons after its concept was leaked, however.