I think I have a new theory for when the Terminal 5 expansion will be completed.
So you know how Delta currently operates out of Terminal 2, but usually only uses regional jets, A220s, and Boeing 717s because the gates they have are only for smaller aircraft? Well, once Delta moves to Terminal 5, they will have access to bigger gates that can support bigger narrow bodies and even a gate for a wide body. This image below shows Terminal 5 after renovations, and all of the orange planes represent Delta's new gates.
So I went on Google Flights and played around with dates, and noticed that Delta started switching the regional jets, B717s and A220s with A319s, A320s, B737s, and even a decent amount of A321s staring June 5th. Even the short routes like Minneapolis show that the regional jets have been switched to bigger aircraft. So I wonder if by then, the Terminal 5 expansion will be complete and Delta would've moved there so that they have gates to operate the bigger narrow bodies.
So could June 5th be the target completion date for the Terminal 5 expansion?