Were we to remain in the Garden of Paradise forever if Adam had not sinned? I read this statement from the Catholic resource. Q. 255

A. We were not to remain in the Garden of Paradise forever even if
Adam had not sinned, but after passing through the years of our
probation or trial upon earth we were to be taken, body and soul, into
heaven without suffering death.

What is this teaching based on within the Catholic Church?
There is a similar question and the answer that coincides with this statement mentions Genesis 3:22

Then the LORD God said: See! The man has become like one of us,
knowing good and evil! Now, what if he also reaches out his hand to
take fruit from the tree of life, and eats of it and lives forever?

But I can't really see how that verse says we were not meant to stay in the paradise.
There are two considerations here. First is that Catholics do not view the creation story as strictly literal. When we talk about the "garden of Eden', that certainly could have been a real place, but more importantly, it is symbolic of the harmonious existence humans held with the qualities of original justice, original holiness, the preternatural gifts, and the supernatural gifts. Were we to remain trapped in a walled off garden forever? No. Did God intend for us to enjoy the aforementioned gifts He gave us in the beginning for our entire extent in this world? Yes. 

Second, one of the many titles Catholics give to Mary is "New Eve" because Mary embodies everything Eve meant to be before she chose against God. Mary is held to never have died;however, she is not here on Earth either. Catholics hold that Mary, after her time on Earth, was assumed body &amp; soul into Heaven. It is reasonable to believe that had Eve never sinned, she and Adam would also been granted Heaven and spared death. 

In short: that resource is correct with respect to Catholic beliefs.