What does Genesis 15:15 mean?

After revealing to Abram, perhaps in a dream, the affliction his future family will face in captivity, serving another nation, God informs Abram he will not live to see any of this. Instead, Abram will "go to his fathers"—a common reference to death—in a time of peace and at a good, old age. Of course, at this point in time, Abram is already somewhere between 75 and 85 years old (Genesis 12:4; Genesis 16:16). God's words about Abram's immediate future are a comfort, but they also let Abram know not to expect to possess the land of Canaan in his own lifetime. Instead, it will one day belong to him through his descendants.

This promise comes along with God's prior reassurance that Abram will, in fact, see a natural-born son (Genesis 15:4). As it turns out, this promise itself will take some time for God to complete (Genesis 17:16–19). In the meantime, Abram will be renamed as Abraham (Genesis 17:5), and will attempt to "help" God fulfill His promises by having children with his servant, Hagar (Genesis 16:16).