It's difficult to say right now whether or not there will be a sequel to the popular series, Game of Thrones, starring Jon Snow. While HBO has not made an official statement on the matter, there is some speculation that the network may be developing a formal sequel.
At the moment, nothing has been officially confirmed or formally announced by HBO. However, some fans have speculated that HBO may be developing a new series or movie based on the world of Game of Thrones, one that would potentially feature Jon Snow in its storylines.
It's also worth noting that some Game of Thrones spinoff series have already been confirmed by HBO. While these series are not centered around Jon Snow, they may provide clues about any potential sequels for the character. For example, the network has confirmed that there will be a new series by George R. R. Martin entitled "House of the Dragon," which follows the Targaryen family during the early days of the conflict in Westeros.
Ultimately, only HBO can provide any reliable answer to the question of whether there will be a sequel featuring Jon Snow. Until an official statement is made, fans will have to wait and see if a new series or movie featuring their favorite character is in the works.