EDIT: Really, whether they were blocked or not makes no difference. Why was there a Tree of Life if man was already made to live forever? And if "live forever" did not mean physically, do we deduce that Adam was not saved since after the fall he could not access the TOL? Or is it possible man was never made to physically live forever, even pre-fall?
Just for consideration, consider the question of how man gains eternal life.
Most would agree man was in relationship with God in the Garden, and whether Adam would have lived forever or not if he had not disobeyed God might be answered if we can narrow the field of possibilities for how man can have eternal life.
Positionally, the redeemed are said over and over to have eternal life when they are saved. Most would agree to that.
Most would agree that man is glorified before entering the eternal state, where we will once again see the tree of life. That would suggest strongly that eternal life has another source than the tree of life, wouldn't it?
Silly question, I know.
Revelation 22
1And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.
2In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.
3And there shall be no more curse: but the throne of God and of the Lamb shall be in it; and his servants shall serve him:
Notice that there is the tree of life, which is for the healing of the nations, which I take to picture the reversal of the Garden Event which brought the curse (upon the nations, so to speak), rather than a remedy for, lets say, skinned knees upon the streets of gold.
And there shall be no more curse: again, a reversal of the Garden event, man's separation from God, a restoring of the relationship Adam had with God.
14Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.
John records these words, and again I ask, could this not be viewed as speaking of man restored?
Note also:
17And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst come. And whosoever will, let him take the water of life freely.
The water of life: is this not the very river mentioned in v.1?
And will we also need to drink of this river, as well as partake of the leaves of the tree of life?
I would say no, eternal life has but one source, that is, God.
In the Garden we see:
Genesis 3
17And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life;
18Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field;
We see that all of creation was affected by a curse through Adam's disobedience. Prior to the fall, no thorns, no thistles, that would seem to be a reasonable conclusion.
Looking back to this...
Revelation 22
3And there shall be no more curse: but the throne of God and of the Lamb shall be in it; and his servants shall serve him:
So, if we look at Adam's state before he fell, and ascribed eternal life to him, it would only seem reasonable to conclude that consistently in scripture we are taught that eternal life has but one source, that is God. I would agree it is speculation on our part to be dogmatic about Adam's state, whether he would die physically or not, but, if we are dogmatic that Adam did die "the day" that he ate of the tree of knowledge of good and evil, we might conclude that Adam died spiritually.
Access to the tree of life may have extended his life physically, but I do not think we have to equate the result of Adam eating of that tree with eternal life" which has but one source, the Eternal God.
As I said, submitted for consideration.
God bless.