While I don't hold with christian tenants much, I do think for sure that aliens walked among us in the past and that memory of them remains with us in the form of various 'myths' like the giants, but also the elves, unicorns, and other beings we 'know' of thru fairy tales, and other stories.
I am guessing the government will admit to the greys, though, because they are building us up with all the media stuff, like movies & TV shows. Also there is a huge influx of 'alien' images into the pop culture, like 'fun' jewelry and ads that use the greys/spaceships for a humorous take on things, etc. There is just too much attention being given to them for it to be a coincidence, I feel. They may be doing the introduction as a way to consolidate power here, i.e. scare the bejeebers out of Joe average and then show him that if you go with the NWO bunch, you will be on the same side as these otherwise 'superior' and scary aliens. I am guessing it could be quite the motivator for the average man/woman.
Also I wonder how scientology is going to take that revelation, as one of their most prized and closely held secrets is that they are supposedly in communication with the aliens. Of course it could all be the same house, different doors, eh?