Punishment or an Act of Grace?
It is interesting to me the timing of God forbidding Adam & Eve to eat of the tree of life. It appears that up until their sin, they had access to this tree--the only exception placed on them was not to eat from the tree of knowledge of good & evil (see 2.16-17).
In that way, I wonder if it isn't possible that while this is a punishment (death came about because of that sin), is it not also an act of grace? God chose from this moment on to not allow us to live forever in a sin-infested & curse-inflicted place. Rather, He began the process of bringing about the restoration of the perfect creation He originally made.