I've bumped this to the main forum since we have a confirmation that production is beginning for this, and more than likely for 2017. (can't see why it would miss it).
Since those old rumors for 2016 are celearly not happening, this rumor that was posted a few days ago seems way more likely. http://www.dayherald.com/prometheus-2-release-date-revealed-plot-aliens-to-be-introduced-and-much-more/5175/2/
I think March would be a good fit for it.