What do you consider an extended tour? I am not sure if anything that I have done or would be likely to do would qualify. For me, I find that 3-6 months is about as extended as I currently have any interest in ever doing.

That said... I wouldn't worry any more about the future than I already do. I figure that I am retired and can tour as cheap as I can live at home. If I didn't have a wife, house, and dog that would be even more true.