It's not a crush anymore when you realize you don't get butterflies anymore after everytime you talk or do stuff together. It's when you realize, even though the bubbly feeling is gone, you still want to stay with them .. because otherwise you'd break and you think they're the best person. The feeling you got that replaced the bubbly 'crush' feeling is much deeper and stronger.
It's when you're comfortable around each other and can discuss anything together without embarrassing each other is when the crush is gone, and love has taken in.
At least, to me it is.