E3 is tomorrow, meaning that this will be the last day for rumors and speculation.
Come tomorrow, Halo 2 Anniversary will either be confirmed to exist, or not.
343 not showing Halo 2A doesn’t necessarily mean that they aren’t working on it, but we’re getting rather close to release to still be keeping it under wraps.
Announcing Halo CEA so close to launch, they skipped the teaser trailer foreplay and went strait for the gameplay trailer instead. I imagine that, if they did, 343 would do something similar.
Unless they put out the teaser at E3 and waited until SDCC or Pax to show gameplay.
If ther is an announcement at E3, I’d personally like to see an updated version of the original Halo 2 Announcement trailer here, and then move into showing some gameplay from Outskirts.