Well, if they are 60% complete (although easily found online sources say anywhere from 40-70% all in the last 2 months, and they have been going at it heavily for more than 3 years, that portends another 2 years until its really built. Then all the testing, and not just for their various clearances, but how about the baggage system - you know, the kind of thing that has delayed airport or even just terminal openings for 18+ months all over the World? Fire suppression system, oh yeah, access roads, trains and the like. This is not like building a bridge that does not actually connect to a new highway for many years, or a train that can only go to 1/10 of its proposed stops for 5 years, etc.
They have spent countless billions in TK and IST and cannot blow it just to make a ceremonial date and close down the existing airport, that is why every pilot I know, as well as many actual airline execs familiar with IST basically said what I said. No it won't be 2023, but it will not be before 2020, and can easily push into 2021.
The Dunya article says absolutely NOTHING, except that if they close IST before the end of 2021, they owe compensation to TAV. Yes, everyone knows that. My point is that they extended with TAV through 2021 in 2014! (actual serious negotiations for the previous 18 months or so), you know, at the time that they had ALREADY PLANNED the new airport (which at that time they had even said it would be open in Q1/2017!)........which means that they were taking precautions OR that that is in fact their real dropdead deadline.
Also you do not construct 8 new gates (or 4 A380 gates) and level the airport infield and do a bunch of other things in mid to late 2016 if you were planning on shutting the whole thing down less than a year later - which is what their stated plan was at that time. This is looking more like DWC and DXB all the time (wasn't DWC supposed to take over everything about 4 years ago? Yet they still built a new terminal at DXB - billed as the World's biggest, and all that is at DWC are some cargo and LCC carriers.