When was the last dev. comment concerning progress on the new UI? Will it be complete by the end of the year? Next year? No attempt at sarcasm here, BTW.
You can keep track of their progress yourself by paying attention to patch notes. If they release new 'window.XML' that's the old UI, 'window.HTML' is the new UI.
If you remember it went from a bullet point on a producer letter. And discussion about how great it was going to be and how overdue it was happened here.
Then 6 months - a year later we were told they would be releasing the new UI window by window, a few each patch.
Then that cadence slowed to often having patches with no new window.
How many windows are there in total to be changed? How many are done so far? Don't worry about the maths. I'll show you how to know.
Here's an Oracle tip for predicting the future with high accuracy. The better you remember the past the more clearly the future comes into focus.
We can see from the history, the 'new UI' has never been a top level priority. And it was pushed even farther on the back burner over time.
There is only one person working on it, and they get pulled off for other things that 'take emergency priority', which is how they have worked since the Sony days. I've criticized them for the 'all hands on deck' mentality before. It's a matter of opinion, I've seen people here who support that in a software development house. You can formulate your own opinion of the effect that has on the UI getting finished.
Bottom line, after you do the calculation, you'll arrive at the same conclusion they reach.
They can't give you a time because there's no end in sight.