Source: Halo 3 Remaster Is Not Happening, Microsoft SaysHaving already released "Anniversary" editions of Halo: Combat Evolved and Halo 2, Microsoft won't follow those up with a remaster of Halo 3, at least not yet.
Writing on Reddit as ske7ch343, Halo community manager Brian Jarrard said, "OMG stop. There is no Halo 3 Anniversary." This comment came as part of Jarrard's confirmation that Microsoft won't show Halo 6 at E3 2017 next month, though it will have "a little something" to reveal for a different project.