At least one of the people "providing" those rumors appears to spend all of his free time on a daily basis gleaning rumors from all the forums and blogs out there. Not that the service isn't useful, but he does not ever appear to me to have any sources or original new information of his own. And it does appear to be an obsession to post as many rumors as possible, I guess every forum has someone like that.
And you have to love the one that starts out "don't believe me if you don't want to", as if we needed permission to be skeptical. I guess it's a reflex defense against the inevitable forum trolls that attack every rumor.
It is my understanding that Necrons are long done, so I don't have any trouble believing their release is fairly imminent. They've probably been in their new boxes for many months.