Hypothetically? Yes.
Realistically? Not a chance in the world.
This discussion for all practical purposes is for naught because one of the primary figures of the article, Gary Portnoy, has a career much more storied than his big hit, " Where Everybody Knows your name" and he has an estimated net worth of $13 million. The discussion is further muddied as both Roger and Herb point out, in this instance in particular, Mr. Portnoy also had a co-writer. Co-writer Judy Hart Angelo also has a much larger portfolio and career beyond the one song they are most famous for and appears to have a new worth around $12 million.

However, there's nothing hypothetical about the real possibility, regardless of the time to do so or the source from where it originates, today, it's possible to accumulate enough dollars from one hit song to retire. It's not an impossibility that a song from Herb's catalog get chosen for a major production movie and for whatever reason, it's possible he gets offered $150,000. Likely, no. Impossible, no. It's possible a mainstream pop star selects and records their version Roger's song recorded by Trace Adkins 25 years ago and it becomes the biggest hit of the last 10 years. Likely, no. Impossible, no.
Every day someone, somewhere through no effort of their own to create it, receive an inheritance, find they own something that has extreme value, sell a piece of real estate, receive a settlement, or win a lottery that changes their life. Every day someone, somewhere through efforts of their own to create it, invents something, writes something, sell a song, book, game, or app, or retires and cashes in a retirement account worth tens of thousands or a million dollars.
The odds of any individual making it writing a hit song is akin to any individual making it big as an NBA basketball star. Many will try and most will fail, but someone always makes it. The odds are not impossible.