If they wait until January to reveal the Switch 2, it's almost certainly not coming by March. There wouldn't be enough time to promote the system.
I don't necessarily agree. Wasn't the original switch only announced 3 months beforehand?
The switch also followed the Wii u. Even if there's a very short marketing cycle, it's still likely to sell out right away depending on inventory and launch titles.
Not that it's going to happen, but I don't think a 2 month announce to release is going to hurt it whatsoever