Hehe, I somehow find that funny: Usually, we try to discourage the TEs from planning for old age. Here is (finally) a case where it would make sense to design the house for a lifetime, but you don't want that. I don't think the floor plan is wrong, you know what you want and what is important to you, and you plan/build accordingly. I would probably pay a bit more attention to the resale value if you are already planning that. So, for example, don't neglect the kitchen too much. Otherwise, I recommend thinking about the connections in the kitchen and bathroom early on, since it's rather difficult to impossible to change anything there after construction. Maybe the wall between the kitchen and living room should only be drywall and without any pipes if possible, so buyers can easily remove the wall for an open kitchen.