Yes, like anything that its worth preserving. Like a car or an airplane with time parts and pieces degrade and after many years little or nothing will remain from the original boat/car/airplane.
The question here is: It will deserve to be preserved for posterity as a part of human naval patrimony? If so costs are not taking into consideration if not all things, between them boats reach a point where the value of what you invest to maintain them is bigger than the resale value they have and maintain them it will no longer be a logical operation.
That's why cars are dumped away. Most of them would not have any problem to keep going if repaired. It is just not worth it.
I guess that one of the reasons that will lead to the disappearance of many old boats on the US will be the raise of costs to maintain a boat, I mean raising costs in Marinas restrictions to having a boat permanently moored on public waters. That has already happened in Europe and I guess it is happening in the US.
If you pay a significant amount of money to have a boat at the marina it makes no sense having a boat with almost no commercial value and one where you have to invest regularly considerable amounts of money to maintain it seaworthy. Lot's of money anyway for having an old boat that will perform poorly if compared with a modern one.
The exception, like in the cars or airplanes it will be the ones that are maintained almost exclusively by their owners but that implies a huge knowledge in many areas and they have to pay for the materials anyway and the spaces were they are allowed to work on the boats are becoming scarce.
Also, some can do it, but while they are doing it, they are not sailing and that has also a value since boats can live forever but not us