So the Beyonder may be sending out that signal as a lure or trap. But here’s another theory: Marvel Studios often takes liberties with characters from the comics, sometimes combining aspects of two or more into a version expressly designed for the big screen. If Kang is supposed to be the Big Bad of Phase 4 (and perhaps even some of Phase 5), it’s not unreasonable that Marvel might graft some of the Beyonder’s powers and motivations onto him.
The Fantastic Four
We know that a new movie starring Marvel’s First Family is finally coming, this time from Marvel Studios itself. And we know that Reed Richards can find a way to travel between universes as well as through time. Plus in the comics at least, Kang is possibly a distant descendant of Richards. Since the MCU until now has given no indication that the Fantastic Four exists, could that signal be coming from a version of the Four that does exist in a different universe?
It’s long been suspected among fans that the Quantum Realm (in which signs of civilization have been glimpsed) could play an important role in the introduction of the Fantastic Four into the MCU. But that signal, generated either by the Ten Rings or from somewhere in the multiverse, could also be coming from them.
The Celestials (from Eternals)
With the mid-credits sequence indicating that the Ten Rings are much older than first thought, is it possible that they are actually technology created by the Celestials?
The Celestials, of course, have been around almost as long as the universe/multiverse itself, and have seeded countless worlds in the cosmos with life. On Earth, they created “normal” humans, as well as the Eternals and the Deviants, and return periodically — we’re talking time on a cosmic scale here — to see how their experiments are going.
What if the use of the Ten Rings activates the beacon and sends a signal to the Celestials that it’s time to come look in on their little planet-sized lab? The Celestials operate on such a vast span of time that even Wenwu using the Rings for a millennium would seem like minutes to them. With the ongoing conflict between the Eternals and the Deviants seemingly coming to the fore in this November’s Eternals movie, it seems likely that a Celestial will show up to sort things out. That Celestial might also be very interested in finding out why the Ten Rings have been activated.