For some staff/employers it works well. It's nothing new. Where I worked in the 80s, we had a couple of staff permanently WFH who just came into the office for a couple of hours per week to pick up/drop off work. We also had a local tax inspector who worked from home - she even had a separate direct line phone installed for taxpayers to ring her directly.
"Blended" working between home and work was already happening more and more due to the internet, fast broadband, mobile phones, etc. Covid has accelerated the process.
BUT, it won't work for everyone. Some staff will still need to be at a workplace due to the requirements of the job, i.e. staff who have to train/mentor new/trainee staff. There'll also always be a need for "face to face" meetings, team work, etc. If expensive equipment is needed, employers can't afford to give it to every staff member, so staff will continue having to go where the equipment is.
We've just swung from one end of the pendulum swing to the other. As we come out of covid, the pendulum will move back towards the middle. More staff will have to return to their workplaces, for many it will be a mix between WFH and their workplace.
It's wrong to say that productivity and efficiency is the same. It isn't. Customer service levels have fallen through the floor in many organisations due to staff WFH. Customers accept that short term, but if customer service/quality levels don't rise again, then the organisations will start to lose customers.