Due to the ongoing legal proceedings surrounding the Microsoft acquision of ABK, Microsoft had to make a declaration on the competition posed to them by Nintendo, wherein they mentioned two platforms; Nintendo Switch, and a second system which Nintendo had "Redacted" in the public release.
In the documentation this shows up as "[REDACTED]".
This is as close to an official recognition as we've ever got, so people here have begun calling the next system the "[REDACTED]" or "Nintendo Switch [REDACTED]" to avoid the debate over the possible names. Originally as a joke, now in earnest as a way to avoid either ambiguous language ("The next Nintendo system") or fan-made names ("Super Nintendo Switch").