At the end of , Peter Parker seemingly passes the mantle to Miles, letting him take over the role of the primary Spider-Man in New York.
However, that doesn't mean that he is the only Spider-Man in the city, and there is evidence that he will not be the only one in the next game.
In fact, I believe that that will be far from the truth, and there will be more than just 2 Spider-heroes roaming New York in the sequel.
While Miles and Peter have starred in the past games, the roster of Spider-heroes is long and wide. Spider-Man's rogues gallery is just as deep, so sometimes it takes more than one hero to win the day.
This can be seen in each of the past games. Even in the first game, Peter needed Miles and MJ's help to win, Miles got help from a number of people in his solo game, and both of them were needed in the last game.