I get where you're coming from - it'd be great to know when the next update comes out, but unfortunately that's not really something I can predict. When it comes to software development, unforeseen problems are practically guaranteed and will throw off any initial estimates.
This is a well-known phenomenon in programming. A famous example is Valve Time, proving that even a company as large as Valve can't make a useful ETA (and of course Mojang has plenty of similar examples).
Moreover, ETAs often lead to a cycle of hype and disappointment. Even when people are told that ETAs are super inaccurate, it's just human nature to take them at face value and feel let down when a promised deadline isn't met or a promised feature isn't included at that time.
In the end, I really don't want to over-promise and under-deliver. I prefer the opposite approach: not announcing anything until it's basically ready to release, and then, hopefully, over-delivering with a surprise update. It might not generate as much hype, but I find that this approach feels more honest and helps to manage expectations.
I hope that makes sense!