The solution that everyone goes on Zoom, regardless of whether or not they are sitting next to each other. Pretend the team is fully remote, but still take advantage of organic, local interaction to skill up new developers. We were coincidentally doing this in my workplace 6 months before COVID took off.

If WFH becomes fully accepted, I don't think many employees will choose to commute 30-60 minutes to spend their days at the office instead of staying home with their spouse, kids, and pets.