Still flawed. What if they buy the house under appraised value? What if the house goes up in value? Over time you will pay down the loan etc. Too many variables to make a blanket statement about refiing in the future.
Pools are an interesting thing and hard to quantify how much value they add to a house. People who want them will pay extra for them. However, the majority of people dont want them so it reduces the demand for houses with pools. There really is no simple answer to how much value a pool adds or not.