The Golden Ending is the result of the loop continuing for several billion years
.
The sun's transformation into a red giant evaporated the ocean and turned the sky red. The inhabitants of blackreef and some extremophile bacteria are the only life left on earth.. The temporal anomaly is a breach into the Void.
It seems pretty solid that Deathloop is in the future of the Dishonored franchise and we already know from Dishonored 2 that certain kinds of messing around with Void magic can also mess with time, as we saw at the Silton mansion. At some point someone tried to do something huge with Void magic on Blackreef and since no-one was keeping in an eye on that sort of thing any more the resulting anomaly went unchecked until Horizon then AEON started poking at it. Egon is a descendant of the Outsider
Their character models look similar enough to be related, and having a family story of being descended from a literal god would push you to to studying the supernatural. At the very least, it's a huge missed opportunity. The low-chaos runs of every Dishonored game and DLC are the canon ones anyways. Why not make that connection? It would be especially sweet as everyone calls him crazy while the player knows its completely true. The Slabs are just Sufficiently Analyzed Magic versions of the Outsider's Mark
Shift is almost identical to Blink, and others have similarly interesting behavior that implies they're in some sense "magical", like the Nexus' ability to identify and synchronize living beings. They even both involve "merging" with the user's left hand. As such, they would also fail to function in the presence of Overseers' music boxes, which the field nullifier might be a more advanced version of. (Or perhaps less advanced, and discovered through an entirely different route of inquiry.)Past Colts have been intimate with EVERY other Visionary (except Juliana, of course) at some point in an effort to find some way to break the Loop.
Since he realizes/realized killing every Visionary is necessary to break the Loop, getting close to them (very close) to suss out any vulnerabilities at all would only be logical. The floating letters from other Colts are very familiar with the Visionaries and their habits and hideouts as well. It's not like he wouldn't have time to figure out how to win them over, either, even through trial and error.