I'll be worried (for a December release date) if we don't get any substantial update by the end of June 2017.
As for the actual situation, just read (maybe several times) what Suzuki San said in the last "progress update":
“I have been absorbed in developing the game and I stay in the studio all night time to time. My life is all about Shenmue day and night.”-Yu Suzuki
They are hard at work right now. This is the only reason we don't get updates. That also means that they are doing everything that is humanly possible to create the best Shenmue 3 they can.
We have waited for over a decade to get Shenmue 3. Yu Suzuki waited for over a decade to get the opportunity to make Shenmue 3. I have faith. He won't disappoint us, even if we have to wait a little longer to get out of this cave.