Think of it this way. If you get 10 hours of usage per 100% charge today, in three years you will only get 8 hours per charge. In 6 years your battery might only give you 5 hour of usage per 100% charge. And yes, the battery will eventually fail. At that point you have two choices. Buy the iPad (9th Gen) or buy a new battery, if you can find one
Facts are the first casualty of bad information.
There is an issue reported about issues with the battery indicator on the new iPads. It sounds like a software tweek will come out in the near future to fix it. MacRumors has the story.