It's totally plausible Reed Richards bought the Avengers Tower and it'll soon become the Fantastic Four's headquarters, aka the Baxter Building. During Disney Investor Day 2020, producer Kevin Feige announced a new Fantastic Four movie is in the works, and Jon Watts, who directed Marvel's Spider-Man: Homecoming movie trilogy, will helm the film. Since the Baxter Building is supposed to be located in Manhattan just like Avengers Tower, it's easy to see how the two could become connected.
And that's not all! An easter egg in Spider-Man: Far From Home may point toward the Fantastic Four owning the Avengers Tower in the future. At the end of the movie, Spider-Man swings by the newly redesigned building, and in the background, there's a sign that reads, "We Can't Wait To Show You What Comes Next." Underneath the sign is the numbers one, two, and three. There's also an arrow pointing toward a question mark. Fans think it's naturally supposed to be a number four, which could tease the Fantastic Four will take over the Avengers Tower next.