My employer used to be office based, four major sites, dozens smaller sites, big company.
Customer facing staff can't really change roles but everyone else is now flexible. Work from home unless key meeting - I've been in 3 times since lockdown for about 2 hours apiece and happy to keep it that way, saves me a 1.5 hour commute each day to the office - each way as well.
Our start and end times are fairly flexible, again you can just mug off a meeting but I can sleep in until 09:30 and work extra, or finish early etc without getting approval or anything like that. As long as you do your work no one cares.
Staff morale is great, work life balance is excellent.
The biggest opponents of this will be people who didn't get to do in their day, just like working from home.