We all know that the Direwolves represented them but it also foreshadowed their "futures" somewhat.

Ghost- He was sent to the Wall by Jon before the battle of Kings Landing and Jon was sent back to the wall- again.

Summer- He might have died but Summer peaked when Bran was declared king. He was truly the child of the Summer.

Nymeria- she was sent away by Arya but she discovered the rest of the world and made a pack of her own. Like what Arya did afterwards.

Edit and addition: Also when Arya saw Nymeria in the woods, Nymeria created her own pack which can symbolize Arya being reunited to her pack.

Lady- well she also died early but Sansa did become the Lady of Winterfell and later on became its Queen. Also the death of Lady could represent what Sansa had to go through. From a Lady to become a Queen she must learn and let her old self die.

Greywind- well the name says it all. Robb didnt have much color after the Red Wedding.

The only one that didnt make any sense to me though is Rickon and Shaggydog. Well yeah they both died but I dont see much representation aside from that.