Calling it now. Finale and whoever big bad ends up being is defeated once and for all.
STAR: Marco, you've been my squire, my confidant, and my best friend, and I can never thank you enough, but, it's time for you to wake up.
MARCO: Huh, Star? What do you mean wa-
STAR: I'm sorry Marco, goodbye.
(Flash of magic/light, Marco wakes up in a hospital bed. His mother and father are there, Rafael has a tinge of gray and is slightly overweight. Angie is a bit haggard, hair slightly lighter brown than her last appearance).
ANGIE: Rafael, rafael, he's awake, go get someone! Marco, oh thank goodness you're awake.
MARCO: Huh, Mom? What's going on? Where's Star?
ANGIE: Oh sweetie, I'm not sure I know what that means. Don't you remember?
MARCO: Remember what?
ANGIE: (slight sob) Oh, Marco. You took a bad kick during karate. Y-you've been in a coma for almost two years.
Focus on Marco's face in shock.
Later we are back in the Diaz house, the human characters are leaving having been by to visit and wish Marco well.
MARCO: Bye Jackie, bye Janna, see you guys later.
Marco goes up to his room and sits down at his desk, a forlorn expression on his face.
MARCO: I can't believe it wasn't real. I can't forget, I WON'T forget.
Marco takes a piece of paper and pencil out of his desk and starts scribbling furiously. Final shot of the series is pic related.