Welcome to the forums. I like that your're visualizing your ideal world. It really helps to know what you want out of polyamory. The next step is actually trying to get it accomplished in the real world.
How would you visualize broaching this subject with hubby? Would you just have a heart-to-heart, or would you maybe mention the possibility while watching some poly/open scenes on TV or a movie?
What are you prepared to do with ex if you never broach the subject with hubby? Will you do some legwork first to determine ex's wife's feelings on the subject? How will you feel out the ex to determine his true intentions?
Sorry for all the questions, but your post intrigued me.