Okay, so a new rumor has surfaced, so as always, grain of salt.
NateDrake mentions
in his podcast (start at the 49 minute mark) that Switch 2 reveal happens in Late January /Early February 2025, followed by a major event in May 2025, and release in June 2025. This is all hearsay from him so nothing official. Don't take it as fact.
(PERSONAL SPECULATION FROM THIS POINT ON) If this is true, however, and assuming the game Sakurai started working on April/May 2022 is Smash 6, I think there's a good chance the reveal might happen in the May event. Game would be in development for 3 years by then which is enough to have footage to show and having Smash revealed right before the console release is a good way to get people hooked on the new system.