Once one dreamed, they were no longer who they were before. They weren't who they could be either, or who they dreamed they were. Instead, they were somewhere inbetween.
And even when someone dreamed to the very end, they weren't who they were before or who they dreamed they were. They ended up being someone new, molded by experience.
Ahsoka hoped who Anakin became was less the Sith Lord, and more the Jedi Knight.
"I couldn't stay, Anakin. You were the only one in my corner, but my path had to take me in a different direction."