I don't want to sound condescending, but if being forced out of the job means end for your relationships built for years, maybe these relationships weren't built as they should. They should have been built with the people as people, not coworkers, and definitely not using company as the communication ground.
First thought was whether they meant corporate political capitol transactional relationships.
Second thought was maybe they meant that, inevitably (or so it seems, probably thinking depressed), they'd drift apart, since everyone's busy with family and work, and around the workplace was the only times they'd have to interact.
In the latter, even if you have beyond-work social relationships, the opportunities to interact outside of work and the lunchtime might tend to be like "drinks after work", and effectively disappear as well. If that was your mode while working together, that's fine, and probably you don't want to see even more of each other then. That doesn't mean you weren't seeing them as people beyond coworkers. So, once no longer working with each other, you both need to actively change things to make opportunities to interact.
Good point. I wonder how much in-office work contributes to this. Because if you are trapped inside an office building for 8+ hours with essentially randoms, most people will start getting to know each other at some point, because there is no other choice, and after work and commute there is no time left for anything else.
I feel sad for the author.
So the 40 hour work week gives rather little time to properly socialize, even less if you have family obligations esp. kids, especially when people move around as much as they do now.