According to the newsletter, the original deal that was struck contained a stipulation that boils down to, if Spider-Man: Far From Home clears $1 billion at the box office, Marvel Studios would get to oversee a third solo Spider-Man movie.
However, following the relative failure of The Amazing Spider-Man 2, Sony cut a deal with Marvel Studios back in 2015 that allowed for Spidey to appear in the MCU.
We have some new, very fascinating details regarding the contract that exists between Marvel Studios and Sony, which allows for Spider-Man to appear in the Marvel Cinematic Universe.
Just as a refresher, Sony still actually owns the rights to Spider-Man and his rather large supporting cast of characters.