Yes, and Paul speaks in concepts quite often, He used Sarah and Hagar as an allegory of the two covenants in Galatians. I don't think that Paul believed that there was a city in space that was going to descend on the earth. Heavenly is an adjective, heavenly doesn't mean in Heaven, but rather having qualities of Heaven. I think we're getting into things that haven't been established from the Scriptures. Let's look at the passage.
I'm not talking about a city in "space" either, that's a strawman. Obviously we don't hold that heaven exists in the same dimension as this. They use references to above though as referring to heaven.
The present Jerusalem and the Jerusalem above are contrasted in Galatians 4, and that we belong to the Jerusalem above, we are citizens of this heavenly city.
22 But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, (
Heb 12:22 KJV)
Mount Zion is where the present Jerusalem is. Paul said, "ye are come". If the new Jerusalem is actually a city in Heaven, then somehow these Hebrew Christians have found a way to travel the. It also would mean that there is a mount Zion in Heaven too. The letter to the Hebrews was to encourage the Hebrew Christians not to turn back because of the persecution they were receiving from non believing Jews.I believe Paul is giving his readers of what is coming in the future. If he's talking about a city that is in Heaven I don't see how that helps is readers in the present.
Let's look at the whole text.
But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering, and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect, and to Jesus, the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel.
See that you do not refuse him who is speaking. For if they did not escape when they refused him who warned them on earth, much less will we escape if we reject him who warns from heaven. At that time his voice shook the earth, but now he has promised, “Yet once more I will shake not only the earth but also the heavens.” This phrase, “Yet once more,” indicates the removal of things that are shaken—that is, things that have been made—in order that the things that cannot be shaken may remain. Therefore let us be grateful for receiving a kingdom that cannot be shaken, and thus let us offer to God acceptable worship, with reverence and awe, Hebrews 12:22-28 (ESV)
Just prior, the author is making a distinction against the Old Covenant represented by Sinai. The New Covenant, here is represented by Mount Zion (instead of Mount Sinai) and the heavenly Jerusalem. If you look closely, everything described represents heaven, and the author then goes on to draw a contrast between heaven and earth. That if the people of Israel refused him who warned them on earth (Moses), how will we escape punishment should be refuse Jesus who warns from heaven.
Everything described in 22-24 is about heaven, or it makes no sense to the context.