I was attending a class at my church last night, led by a 90+ year old mighty man of God, who happens to believe in a pre-Tribulation rapture. During the class, he drew our attention to Hebrews 11:8-16:
 By faith Abraham, when called to go to a place he would later receive as his inheritance, obeyed and went, even though he did not know where he was going.  By faith he made his home in the promised land like a stranger in a foreign country; he lived in tents, as did Isaac and Jacob, who were heirs with him of the same promise.  For he was looking forward to the city with foundations, whose architect and builder is God.  And by faith even Sarah, who was past childbearing age, was enabled to bear children because she considered him faithful who had made the promise.  And so from this one man, and he as good as dead, came descendants as numerous as the stars in the sky and as countless as the sand on the seashore.
 All these people were still living by faith when they died. They did not receive the things promised; they only saw them and welcomed them from a distance, admitting that they were foreigners and strangers on earth.  People who say such things show that they are looking for a country of their own.  If they had been thinking of the country they had left, they would have had opportunity to return.  Instead, they were longing for a better country—a heavenly one. Therefore God is not ashamed to be called their God, for he has prepared a city for them.
He used this passage to show that Abraham understood that the promises of God would be fulfilled in Christ, and in the heavenly Jerusalem.
I think there is some support for the view that Abraham saw “the big picture”. In John 8:56, Jesus himself said that Abraham “saw (my day) and was glad”. But is it reasonable to conclude that Abraham understood the entire fulfillment of God’s promise of the land to be about a “heavenly country”, as Hebrews 11:16 could be read? (forgive me for going back to square one for the moment) I find great difficulty in imagining that Abraham is asking about a “heavenly country” in Gen 15:8 when he asks God “how can I know that I will gain possession of it?” And in Genesis 15:18, when God refers to “this land”, He gives some very specific boundaries. It seems very clear that the promise at least included the physical land.
When attempting to reconcile this with Hebrews 11:10, do we take the “city with foundations” to mean earthly Jerusalem? If so, how do we take the phrase “heavenly country” in verse 16, which seems to refer very explicitly to the heavenly Jerusalem of Revelation?
What could be more “heavenly” than a country whose inhabitants transcend death and inherit God Himself?
That this should be in a literal Land that is inherited “forever” is no contradiction at all.
Even if we discover by ‘progressive revelation’ that the Land will someday be transcended by a new heavens and earth, this does not make the thousand year reign of Christ on earth, or the promise of an eternal inheritance of the Land any less heavenly. For Abraham to regard the promise as “heavenly” certainly need not imply that he understood the distinction that was not clearly revealed until Rev chapters 20-23. It is edifying, however, to consider how remarkably the language of Hebrews anticipates the more developed revelation that we see written several years later by John on Patmos.
Abraham well enough understood the hope as entirely heavenly, meaning miraculous and eternal, transcending of all present limitations. Even when Paul will say “eternal in the heavens” (2Cor 5:21), he is not contrasting this to a real location on earth. This should be admitted even by those who deny a millennium, since even they recognize a new heavens and earth. So even such language as “eternal in the heavens” is not set in opposition to existence on real terra firma, even if it’s the ‘new’ earth of Rev 21:1. See what I mean?
All’s to say, it is not necessary to suppose that Abraham would have understood the distinction between the millennium and the eternal state for him to conceive of the inheritance as heavenly. With you, I don’t think he saw the distinction of Rev 20-21. If he did, it is certainly not recorded. Even so, promise of unending inheritance of a Land, together with all all your children in perfect communion with God, how do you get more heavenly than that?
I think we are creating distinctions between earthly and heavenly that never existed in the Hebrew mind. When the writer of Hebrews (I’m sure Paul), speaks of earthly, he means carnal and temporal, NOT the tangible ‘good’ creation of God that was corrupted by sin and death. Remove the sin and death and make the inheritance indestructible and eternal, and you’ve got heavenly.
In the Beloved, Reggie