Yes, He had to be the prince. I had no doubt about it (well only in the way I doubted that Severus Snape had killed Dumbledore on his orders, in the way that I doubted the author, who might try something cheap just to laugh at the readers).
But you are a good writer. I know that. So there was nobody else except the Harry, who could be the Prince.
I still want to see how Harry explains himself...and how Draco takes it. It's funny how with a minimum of time and resources Harry got rid of all the DE's left.