Probably yes. Psyduck, psyduck.
More seriously, the options I've seen suggested for why developers would be aware of a March date are:
- It's the date they've been told to have marketing material ready for the reveal;
- It's the date that NDAs expire;
- It's the date they've been told to have games ready to submit for prepublication checks if they want them to be ready for launch;
- It's the actual launch window.
I tend to think the last one is the least likely, in the sense that it's the least ambiguous one - if they're told a proposed release date, then they know it's a proposed release date.
The other three options leave more room for developers to be speculating what the deadline means for reveal/release, and therefore, to me, feel more consistent with the ambiguity in the information floating around.
But who knows? Maybe they are all secretly Psyduck with massive headaches.