I've also toyed around with the idea of starting a photography business. I already travel full-time so travel photography comes to mind, I can go into my backyard and it will be different every few weeks.
I like your suggestions and think they can all be helpful for anyone trying to move from hobby photographer to pro. It would not be easy but, as you say, it would take hard work. And hard work is... HARD.
Good luck with your journey from backyard to world travel photographer!