As Robert Downey Jr’s Sherlock Holmes alter ego would remind us, the simplest explanation is usually the correct one.
The most likey explanation is everyone featured in the photo above is meeting about the next Avengers movie. Hopefully, they’re specifically discussing how to make a movie with a zillion characters and keep it from being a disastrous trainwreck.
But I could speculate all day – this is a non story that won’t go away. The only reason to send out this photo was to remind us that they still exist.