Despite what the movie may suggest, Boba Fett did not die in the Pit of Sarlac, assuming you accept extended universe as canon. In the book of Star Wars short stories "Tales from Jabba's Palace" one story details how Boba manages to barely make it out by setting off a series of explosions in Sarlac's belly, albeit at the cost of his mandalorian armour, which is mostly dissolved in the pit.

Other sources reveal that following his narrow escape, Boba was found sprawled on the Tatooine sand by fellow bounty hunter Dengar. Eventually Boba did catch up with Han Solo again on the world of Julibar, but after capturing him, he decided to let Han live out of respect for his long-time adversary, putting an end to their emnity.

Do note that all of this is based on patchy extended universe sources, so it is left open to much interpretation. However, the general premise that Boba Fett is alive and well is definitely an established Star Wars fact, leaving the possibility for him to appear in more stories in the future.