I bought my house 8 years ago with the pool. The liner was vinyl and 20 years old. The old owner hadn't done much to look after the pool and neighbours said they kept it from being green by tossing chlorine in it. What finally did the liner is was that it is a rectangular pool with square corners and the vinyl gave out at the corners. I have a very good pool tech that only does service, and doesn't sell chemicals and products, etc. and he inspected it when I bought the house. At that time he gave the corners 2-3 more years, and he was on the money.

Don't know if this adds anything to the discussion among the knowledgable here, just sharing experience with an very old liner.