In that case your areas of focus should cover everything in your life - now and in the future.
I think defining the projects that are outside your current areas of focus is the only way to grow, to overcome your limits and to have fun.
I don't see areas of focus that have changed much if at all in the last 30 years for me personally. Emphasis on different ones has changed, projects have changed and details have changed but the areas of focus are still the same ones I had 30 years ago. My main areas of focus haven't changed since long before I started using teh GTD method.
Maintain and Support Friends and Family
Pursue a Healthy Lifestyle
Make a Difference
Support my Community
Sure 30 years ago the difference I was making was related to computer SW and now I am running a farm but the focus is still the same. The how has changed and so have the projects to support that but the focus is still there.
I believe if you have a project that isn't part of your defined AOF then you probably have a lurking undefined AOF hidden somewhere starting in your 50,000 ft level. You have some sort of reason for wanting to do the project. I think it's time to review your higher levels to get it all out.