Busking as a singer/songwriter with a guitar is the hardest. As you said, there are tons of others trying the same. However, walking away with wads of cash past the others who have 68 cents in their guitar cases is rewarding. You simply have to be the very best.
Just about anything else is easier...stilt walking, magic, clowning, mime, etc. when it comes to busking. People are still fascinated with juggling - so much so that buskers often refer to them as "Not another fooking juggler..."
Perhaps you should create a whole new show with your guitar show as a backup. You could even end your new show with a rousing song performed "live".