I very much doubt that Adam and Eve would have been assumed into heaven if the Fall had not happened, since the Paradise for which they were made, where they belonged, was in the created world. I think there is a minor theological error common to faithful Catholics which holds that being in heaven is the perfect state. This is not the case. We were made for this world, perfected. Heaven is much better than a sinful world, but we will only be truly happy when the world is remade and we are able to live here with God present among us.
And, yes, procreation would definitely have had a purpose, because God’s very first command to Adam and Eve was “Be fruitful, and multiply, and fill the earth, and subdue it.” That certainly would have been in effect whether or not we had fallen.
However, I don’t see that population is all that big of a problem. About 100 billion people have ever been born. That’s roughly twenty times the current world population – but, we must remember, food supply and distribution would have been much easier in a preternatural world, before Adam heard the words “cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life; Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field; In the sweat of thy face shalt thou eat bread…” It is reasonable to assume that we would have had a much easier time with food had we not fallen. Food would have far been more abundant, and our needs would have been far less insistent.
It is also not unreasonable to assume that the population would have grown more slowly, because we would have been in full control of our passions and our sexuality. Our fertility would have functioned precisely in accord with God’s plan – no more, no less. There is no question that many pregnancies today don’t happen when, in God’s plan, they ought to have happened.
There’d be no little housing so many people, as long as we could feed them; 100 billion people could comfortably fit on the Earth’s surface area with a slightly lower population density than the state of New Jersey.
And, I have little doubt, with 100 billion preternatural, sinless minds working on the problem, we would have interstellar space flight very soon indeed. And once you’ve gone interstellar, your population cap is essentially limitless. There are trillions and trillions and trillions of planets in the universe, and that’s just this universe.
Hope that soothes your concerns.
