Dave Mustaine hints at a massive July announcement in pre-show Istanbul interview: "It's out of this world, I gave you a clue right there
This interview was conducted just hours before the Istanbul show on June 23 and published yesterday. The interviewer is Turkish so it has flown under the radar despite the conversation being in English.
Two things worth noting: Mustaine reveals that the three-year tour was already booked before the farewell decision was made ("we had a three-year tour that had been booked... at the end of the tour I would decide whether I wanted to carry on"), which puts a different spin on the whole "farewell" framing.
He also explains that setlists are built each morning by comparing the previous show at that venue against the most recent show, deliberately rotating songs to avoid repetition across dates.
The other moment worth clipping is around 31:00, where he teases a "massive" announcement coming in July and immediately adds: "It's out of this world, I gave you a clue right there." He told Metal Hammer back in November that he wants the final show to be on the Moon, so draw your own conclusions.