Also, just so people have a timeline sense here are some signs of the times if you wish to know when Alpha 16 is truly soon...
1) Alpha 15.2 has been released
2) Joel has released a series of gameplay videos
Right now we are still in feature preview video mode and the features we have seen are not yet fully integrated into the game i.e. Unplayable without using creative menu.
Once Joel starts posting Let's Plays and exclaiming that everything is playing really well that is when the experimental version of A16 will be Truly Soon.
We still have some time yet to go.