@sun860123,
You asked him to have "break up" sex. He agreed enthusiastically and said that hewould likely want to keep having sex outside of any relationship.
This sounds like good communication on both parts.
It seems to me that if he wanted more than "friends with benefits" he would say so. He has told you the type of relationship he wants, and that is what is possible, If this "friends with benefits" arrangement is what you want, then go for it. If you don't want a "friends with benefits agreement", then say so.
It would be unreasonable for you to stay in a "friends with benefits" arrangement with the expectation that this will return to something with more commitment (it might, but there is no guarantee).
In my experience the easiest relationship after breaking up is friends without benefits. Lot's of people do this and it works well.
So tell this man what you want, and if you can't come to a place where you both agree on a relationship that makes both of you happy (be it FWB, or just friends or something more), then walk away.