No, we can't/won't, because if we do and don't make the estimated time frame, then people get angry and say we lied/broke promises/yadda yadda yadda. We've learned to not feed into that.
We don't know a date at this point, not even a range. When we do and are comfortable with that, it will be announced to everyone and the release will be very soon after that.
Now this, this is what I like to hear! Players will not have to be enflamed because of failed estimated time-frames, as well as all of the other nonsense associated with it. The only downside to that is the constant spam of several hundred messages throughout Terraria’s social media of when a set release date is going to be made! Annoying, sure, but not really detrimental at all!