Aside from being historically significant for the Starks specifically, the crypt is the site for many an interaction that have been important to Game of Thrones' story. It's where we learn the popular version of Lyanna's death, told to us when Robert Baratheon and Ned visit her tomb. In the books, Jon, Bran, and Rickon all have dreams in which the crypt features prominently — it's a source of dread for Jon in particular. Before his death, Ned dreams of Lyanna's statue whispering to him, "Promise me, Ned," which we hear again in the season eight teaser. It's where Peytr recites the story of The Tourney at Harrenhal to Sansa after her return to Winterfell in season six and she finds the feather left by Robert. It's also where Sansa and Arya have their private reunion in season seven. And considering the family news that's about to break in season eight, we have no doubt the tombs will be visited once again, by the one who dreads them the most.
The crypt may also serve a more practical importance in season eight. Not only is it huge and consist of multiple layers, but it also has various tunnels running through it to aid Northerners escaping from trouble. We know there will be an epic battle early in the season and it's assumed that it'll take place either in Winterfell or close to it, since it's the first stop as the Night King's army pours into Westeros. The crypt tunnels could be the key to the survival of some major key characters, especially the members of House Stark. They could lead them to safety outside of Winterfell, or house them during battle. In George R. R. Martin's novels, there is a legend that the daughter of Lord Brandon Stark and Bael the Bard hid within the crypt for months until she reappeared with their bastard son. Perhaps the show will take some inspiration and use the crypts as a temporary sanctuary for some very important characters.