Of course not. The March 6th event had nothing to do with the next Xbox / Durango.
If you are talking about the date BClifford claimed then you're wrong. Again, there are lots of MS internal meetings this time of year and there most certainly was one this past week (4th - 7th) that absolutely did have the new Xbox as a centerpiece for the conference (their F14 START meeting). It was invitation only and featured a deep dive, retail strategies, and software lineup meetings as well as meetings geared towards general entertainment aspects of the platform. The deep dive was the 6th I think.
That was wholly internal and invite-only, so odds of leaks from it are slim to none. This isn't to suggest BClifford wasn't utterly and wholly full of shit. He likely was but I've no idea...I am noting this mainly because I've seen ppl here mistakenly post that there was nothing on the 6th for Durango and they are factually wrong on that. I'd prefer misinformation to be kept in check, hence me noting that TechFest wasn't where Durango was featured.