Who knows for sure that this isn't even a rare condition? In theory, there could be people living among us that are centuries old and might look like 20-30. If I was, I wasn't going to tell everybody. If you travel a lot people won't notice your condition. I believe this is just proof that the condition exists, not the magnitude of it.
There's no proof that she's going to live any longer than a normal human. She's just developing much more slowly than normal. She's also had many severe medical conditions which required intensive medical care. She still has to be fed via a gastric feeding tube. I doubt anyone with a similar condition would have survived the first 5 years of their life as short as 60 years ago.
Well, at the end of the article, there was mention of a 40 year old in the body of a 10 year old boy. We can probably observe him to see if such people can have abnormally long lifespans.
