Interesting, I hadn't read this before but it's exactly what I have observed with my cats. They have gotten dramatically more comfortable with people as they have gotten older. I have often wondered what spurred such a significant change, and didn't realize it was the aging itself.
It's been dramatic when I've seen that with cats. Years of hiding from strangers, then one day they just come out and start sitting on laps.
In my experience it's also typical for cats to get less interested in interacting with other cats.
Indeed. My cats used to religiously hang out in the basement on top of shelving that sits by two ground level windows. Those windows gave them the opportunity to interact with neighborhood cats walking around and there were smudges all over them from trying to fight them through the glass. Nowadays I rarely see them down there anymore as they prefer to simply lounge on upper floor window sills.