I think this is the right answer. For me, I work in embedded and have to talk to lots of people with different backgrounds. Slack communication and even phone calls just don't work when you're trying to learn or explain something really complicated. I think a 1-3 days in the office (depending on what a company needs) would be awesome.

So my company takes a somewhat similar approach to those who can, and those who want to.

We are 90% remote. Most remote employees are in the same area though, so sometimes they commute to the office for weekly meetings or just to hang out and work together.

I don’t live in the same country so I’m 100% remote. However, I still travel to the office ( when there isn’t a worldwide pandemic going on ) a few times a year.

I think giving people the option to work in the office when they want to is the best solution. Keep meetings on skype/jitsi, whatever, but give people the option to attend in person. More people will come than you might think.

I worked at a setup like that, and it was really bad because people were coming on random days. In a set-up like this, people need to have agreed upon days to come back to work

One of the big benefits to companies of WFH is dramatically reduced real estate costs (plus all of the support services required - cleaning, security, maintenance). If you still need your office capacity to support 100% of the staff in the office at a given time, you lose most of that benefit.