(1) I would rather stay within the context of this passage in Genesis and not jump to the book of Revelation as when you do that, you inevitably open up a whole lot of other dimensions that are now needed to be thoroughly searched before you could make any valid and reliable conclusions.
(2) For example, you seem to be working on the assumption that the saved nations mentioned in Rev. 21:24 and 22:2 are the saints – that is, those who through believing and receiving Jesus had been born of God and, thus, already possess the eternal life. But I’ve been familiar with a theology, according to which those saved nations are quite a different group of people – quite different from those who are in the very next verse referred to as “servants of God” (Rev. 22:3). According to this theology the latter ones are the true sons of God, born of God, possessing His eternal life since the
(3) moment of their regeneration. The former ones, however, are merely people who were not believers in Christ (because they had never heard of Him or, perhaps, heard, but only a few things and that wouldn’t count as hearing the gospel), however, they were still spared by God from the lake of fire because their names were written in the book of life (Rev. 20:15),
(4) and because during their lifetime they were doing their best to live according to their conscience (Rom. 2:14-15) – “by patient continuance in well doing were seeking for glory and honour and immortality” (Rom. 2:6-7). These ones don’t possess the eternal life of God, they don’t possess that kind of sonship, however, they still can live forever thanks to the healing that they get from the leaves of the tree of life in the New Jerusalem (Rev. 22:2).
(5) These people include those who at some point in their life provided good treatment for God’s people and didn’t even realize that (Mat. 25:34-40). The men of Nineveh (Mat. 12:41), the queen of the South (Mat. 12:42) and Rahab the harlot (Jam. 2:25) will probably all be among them.
(6) The word “healing” in Rev. 22:2 is crucial. If they are the sons of God, why would they still need healing? A healing from what?! Have the sons of God not already been healed by “His stripes” (1Pet. 2:24) through believing into Him? Have they not yet been brought into His glory, and has the redemption of their bodies not taken place yet (Heb. 2:10, Rom. 8:18-23)?
(7) Have their “vile bodies” not already been changed to “be fashioned like unto His glorious body, according to the working whereby He is able even to subdue all things unto Himself” (Phl. 3:21)? Are they still in their “burdening tabernacles” or they have already been “clothed upon”, and mortality for them has already been “swallowed up of life” (2Cor. 5:4)?
(8) Has the life of Jesus not yet “been manifest in their body” (2Cor. 4:10)? Are they not already bearing “the image of the heavenly”, instead of “the image of the earthy” that they used to bear before (1Cor. 15:48-49)? Have they not yet “put on incorruption” (1Cor. 15:48-49)? Has it not been told of them early in Revelation that “God shall wipe away all tears from their eyes; and
(9) there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain” (Rev. 21:4)? What other healing would they still need then? What kind of power that God has either “overlooked” or failed to subdue do they still need to be healed from?
(10) Another thing is that you seem to assume that there exists only one unique tree of life and that the New Jerusalem and the paradise of God are one and the same place, and, thus, we are talking about the same tree here. However, even this point must somehow be checked and proven first.
(11) If one can readily accept that the tree of life in Rev. 2:7 is that very tree that we have in Genesis – because in both place it is stated that the tree is in paradise, it may still not be the case with the tree of life in the New Jerusalem.
(12) After all, the tree of life and the paradise in Genesis are associated with the old heaven and old earth, while the New Jerusalem is associated with the new ones, and it is “coming down out of heaven” (Rev. 21:1-2) – from the new one.
(13) It is also interesting that in the description of the New Jerusalem, while we are told that to “him who is athirst it will be given of the water of life freely” (Rev. 21:6) – which we can safely assume is the river of life – we are, in fact, never told explicitly that anyone will be eating the fruits of the tree of life.
(14) It does say that the tree will bear its fruits 12 times a year, but we are only told that “the leaves of the tree are for the healing of the nations”. This point also needs to be addressed first.
(15) Therefore, I would rather “linger” within the framework of Genesis for now and see if we can still illicit something solely from this passage.
(16) “exactamundo!” – So, originally the tree of life didn’t have the ability to impart eternal life (immortality) in people, but when Adam partook of the tree of knowledge, the tree of life quickly “got its act together”, “switched its gears” and somehow generated within itself an ability that it had never had before – the ability to impart the eternal life in humans. At the moment I find this theory highly unlikely and even crazy.
(17) First of all, it makes the workings of the tree of life for some reason dependant on what happens between Adam and the tree of knowledge. But why would it be so in the first place? Why would Adam’s action or, rather, his interaction with the tree of knowledge be determining the main function and the nature of the tree of life?!
(18) Why would the tree of life be so “sensitive” to what happens between Adam and the tree of knowledge? And why would God need to create such an “in-case-Adam-partakes-of-wrong-tree”-sensitive tree of life – only to create troubles for Himself of having later to bother to shut Adam’s access to that tree? Would it not have been easier not to create that sensibility in the tree of life at all?
(19) To me, the improbability of this theory goes even higher when I look at its origin. It was put forth for the sake of only one sole reason – to rationalize the possibility that Adam “might’ve partaken of the tree of life prior to partaking of the tree of knowledge” while this possibility is merely a product of our contemplations and has no basis in the Scripture.