I tend to think they were both "real" too. If the tree of life was not real, I don't think God would have had two Cheribum guarding it up until the flood. Just as Satan chose to rebel, God had to give his Adam a choice. Without free will, man is nothing but a robot and God is unjust. Without free will, then God is truly unfair and unjust.
I think if Adam had told Satan to "get thee behind me" as the Second Adam, Jesus, did (note - was Jesus set up to fail? Thank God he didn't), Adam would have had the right to eat of the tree of life, he would have been ruler of the earth, God's regent on earth so to speak, and Christ would never have had to come redeem man - there would have been no redemption necessary. Every thing would be very different today.
As an aside, note the Cheribum's four faces: Man, lion (wild beast), ox (tame beast), bird - i.e., creation. When people came to worship God with burnt offerings outside of Eden, they saw the Cheribum guarding the Tree of Life. I have often wondered if the ancient gods man worshipped were not a corruption of the original Cheribum that Noah and his family saw and passed the info down to mankind who worshipped the "creature" rather than the Creator. Interesting.