Google may have just released the developer preview of Android N but Samsung flagships have still not been updated to Android 6.0 Marshmallow in most countries. Major carriers in the United States are gradually releasing said update for last year's flagships, and it appears that AT&T is going to release Marshmallow for the Galaxy Note 5 tomorrow and for the Galaxy S6 on March 14.
Multiple AT&T customers have reached out to the carrier's representatives and they've been told to look out for the update on the Galaxy Note 5 tomorrow. The customer reps have also mentioned March 14 and March 15 as the release dates for this update on the Galaxy S6. Since it's the second largest mobile carrier in the United States there's no doubt that millions of people are looking forward to this update, and if the information from its representatives is anything to go by, then the updates will soon arrive for AT&T customers.