>>58055966
Even if you look past the alleged Teraleak speculation, you also have to consider that a new Eeveelution needs to synergize flawlessly with all nine other members of the bunch, in order to ensure their color coding and silhouettes compliment each other rather than confuse or detract. These fuckers are cash cow supreme, and a huge part of that is how nicely they co-exist together.
And that's an extremely hard sell without an Eeveelution that's primary green (in the same way Vaporeon and Glaceon can coexist due to being different degrees of blueness), but the problem therein lies that of the existing types, green doesn't exactly work for any type aside from Bug, which doesn't exactly lend itself well to a mammalian species and risks breaking the balance by being the most standout weirdo of the bunch, when Eevee should be the star of the group because it's the launchpad from which ALL of these Pokemon come from.
As such, the only way you'll see a new Eeveelution come into existence is if GameFreak gets the idea for a new type that's presented as green in some shape or form, and is also a type that can translate into a mammalian creature who meshes well with the others of the pack.