"Child," said Aslan, "did I not explain to you once before that no one is ever told what would have happened?" The Voyage of the Dawn Treader, ch. 10
This is simply a marvelous insight, as we human creatures spend so much time dwelling on what might be: what we might want, might create, might change, and so on. Daydreaming. Not that daydreams are bad, but they can be quite delusional and wasteful of time. We can waste our lives with great regret, as Lucy is tempted to do in Prince Caspian, and here Aslan reminds her of this fact yet again. We never know what would have happened, so stop the foolish hypothesizing now.
I learned this first from Bruce McCormack, when the question came up in a theology class, if a passage from Barth envisioned an Incarnation without a Cross, assuming there had been no Fall. McCormack was quick to say, Barth never deals with hypothetical, but with what we have been given, with the theological data truly is. It is the same message, even when doing theology: we are never told what would have happened.
The power of human imagination is vast, to the point of escapism or even personal torment. What would have happened, had we taken the road more travelled? The accomplished poet and novelist Thomas Hardy was tempted, at the end of his life, to wonder and even regret that he had abandoned his early trade of architecture. He began to question if he had made the right choice, or if a greater happiness would have been found in being an architect. Thomas Hardy, asking this foolish question.
At some point the mind must be tamped down, or else it gets in the way, as Lucy is told. Best to live experientially, with what we have and what we have been given, rather than what we might have done, or been. No one gets to know what might have happened.