We're less than a year from Avengers: Infinity War and the centerpiece of that film is expected to be Thanos' quest for the five Infinity Stones, the only problem is, we've only ever seen four of them. There is one Infinity Stone still unaccounted for, but according to Chris Hemsworth, that's going to change "real soon." Hemsworth revealed during a recent convention Q&A that he knows when we'll finally see the Soul Stone, which means it's coming in the near future.
Chris Hemsworth was attending Supanova (via Reddit), a pop culture convention in Australia and was participating in a Q&A alongside Thor: Ragnarok director Taika Waititi when he revealed the impending discovery of the fifth Infinity Stone. We learned the location of the Time Stone less than a year ago, as it is part of Eye of Agamotto used by Doctor Strange, but with less than a year between now and Avengers: Infinity War there are only so many places the Soul Stone could be.
Technically, there are four potential places the stone could be revealed, Spider-Man: Homecoming, Thor: Ragnarok, Black Panther, or Avengers: Infinity War itself. We can probably discount the first and last film on that list. There's no reason to believe that an Infinity Stone is in any way involved in Spider-Man, that story looks to be focusing on very different things. It's possible they could just wait until the Avengers movie itself to reveal the last stone, but they've taken the time to introduce all the others in separate films, so we're guessing that they'll do the same here.
That leaves either Thor Ragnarok or Black Panther as the likely candidates. Of those two, Thor Ragnarok would seem like the more likely option. Thor was going to investigate the Infinity Stones when he left Earth at the end of Avengers: Age of Ultron, also we know that Hela, the Norse god of death will be a major villain in the film. The Soul Stone sounds like the sort of thing a god of death might carry around. It would also explain why Chris Hemsworth is the one talking about the stone, because it's part of his film.
We wouldn't discount Black Panther entirely as an option, however. The nation of Wakanda is technologically advanced and a major source of vibranium, a metal that is mined in the Earth. Perhaps the Soul Stone was found in the same place that most precious stones are discovered, the ground. If Wakanda was able to harness the stone's power in some way, it could be the source of their advancement.
In the end, we're leaning towards Thor: Ragnarok as the most likely place we'll find the Soul Stone. Since the movie comes out later this year, it probably counts more as "real soon" than Black Panther. We'll find out when Ragnarok arrives in theaters November 3.