You can almost be guaranteed that the amount of "softness" will be bigger than you think. Selling the boat with a soft floor, obviously, will greatly reduce it's value. But, on the flip side, it can get expensive very quickly to repair it if you're not doing it yourself. Whether or not you can/should fix will depend largely on your capabilities and the amount of free time you have. The picture below is from my boat. By the way, there was only a relatively small area of softness. Some of the area was perfectly fine and I didn't need to do as much as I did. But this was one of those "as long as I'm there..." kind of things.
This picture is looking at the floor from the opposite perspective and the floor is dirty (and still hadn't put the side combings back on), but it gives you an idea of what it turned into. It's not perfect, but for the way this boat gets used in Maine, it does just fine. It's solid as rock.
