He sure does look like a different horse. Is he changing over time too? Will he become progressively lighter like a grey would?
No, he'll always be roan like this. You can tell if you've got a true roan when the face stays dark. On grays, the face will start to gray out first. Look back at my picture of the girls licking the car and notice Grace's face. She's already starting to gray and will eventually be white. Bluebell, Hope, Bob and Blade will all stay roan, just varing in degree from summer to winter.