The Alchemist ends with the end of Santiago's journey across the sea and sands, right back where he started several years before, dreaming under a sycamore tree. Or does it? The last line of the novel, "'I'm coming, Fatima,' he said" (Epilogue.13) shows us that Santiago's not ready to stop traveling.
The ending, with Santiago coming back home to Spain to find his treasure, kind of like Dorothy finding that she's had the ruby slippers, her way home, all along, wraps up the novel in a nice circular way.
However, Santiago hasn't forgotten about Fatima, and his last words, "I'm coming," show that his journey is far from over. So the book remains open-ended, but we can be sure that Santiago will always be after his Personal Legend after all that he's learned.