Maybe a long time ago - a really time ago - (I remember going to see Raiders of the Lost Ark as a kid without any clue that Han Solo who was in it or what it was about) before websites weren't desperate for clicks (or existed), but these days something always gets leaked. Or studios just announce they're doing something, announcing directors, cast, etc.
I reckon if the AvP series was completed they'd be pimping it. Despite a couple of rubbish live action films, there's still a decent sized fanbase for AvP that would be very excited about seeing this, and they've already spent the money on making it.