As preferable as WFH is for many and as productive as many people can be while working remote, at the end of the day, you can't change human nature.
There is a reason why companies like Google are doubling down in Silicon Valley real estate. They believe that the best, most innovative type of work are the results of organic discussions and unscheduled, unplanned, casual human interactions. So many cool ideas and new projects were the results of a casual lunch discussion even just random hallway chats. You can't duplicate that with Slack messages or scheduled Zoom meetings. The reason for that isn't because of process or infrastructure deficiency with remote working, it has to do with simple human nature.
Even as recently as this summer I've personally seen entire teams get sidelined for important projects because their engineering leadership didn't bother to physically attend an optionally in-person offsite. Guess what, all the most important conversations took place after the Zoom camera was shut off. An entire major initiative came into idea during a casual walk to grab coffee.
As long as companies are run by human there will be politics, off the record discussions, darkroom decisions, favoritism, subjective impressions, subconscious biases, and "out of sight, out of mind" selective memories.
Again, that's just human nature. A C suite executive at a top tier tech company is driven by the same human nature as a caveman. You can't engineer human nature away with process and you sure as hell can't undo them with technology.
Obviously you don't have to care about any of that and there is nothing wrong to focus on other things in life other than work (and many people should), but the inevitable end result will be there will be two categories of workers, even within the same company, if they allow optional remote work.
All the best, shiniest projects will be local right under exec’s noses. The "A-team" will be kept close, or just as likely, the ones who stay close/in office will be recognized as the "A-team". I believe there will be a lot of jobs that will be fully remote at first, then companies will lower comp for those jobs and start giving them less sexy/boring/keep the lights on type of work, and then eventually they will be outsourced out or automated away, yes, even for highly paid FAANG software engineers.
Edit: Some people have brought up the unique benefits of Slack messages like them being async, and by definition clearer and with better record keeping, etc. By people going back to the office 1 or 2 days a week we aren't going to be dumping Slack or Zoom. They will still serve as nice complements.
Edit: Haha I really ruffed some feathers here. I get it, many on HN believe anyone who derive value from in-person interaction are sub-par employees who aren't actually productive. I also do believe that you can have life-long relationships with people without ever hearing their voices or seeing their faces. But I'd just like to remind people that HN is a relative unique group of individuals (even among engineers) that probably prefers dealing with code than dealing with fellow human beings. But the very fact that all of our communication based technology has been progressing to mimic in-person meetings as much as possible (text -> voice -> video -> telepresence -> VR?) says a lot on this subject.