It could. As a father of a 18yo I can tell that they are very well aware of what awaits them in their adult lives.
It is absolutely true that someone else's life doesn't define their own future path, but that doesn't mean they don't latch onto those stories and project the negativity onto themselves. One cannot see the future, so it is quite common to look to others to predict what the future may hold. As you point out, the future is often completely different to what you imagined, but it is what you are imagining that shapes how you feel.
More generally - we can ask if there is data in this study or another one that supports the idea that teen mental health issues are substantially due to their fears of unfair divorce terms they may face 20 years in the future. In my experience as a former teen and father of two, that is simply not happening and I’d need to see the data that says it is before I take it seriously.
They don’t have any real worries about how they will feel in their 30s because they think 7th grade was a long time ago and they don’t quite believe they are actually going to be 30 some day.