In tech roles I really doubt 9-5 in-office working is going to be the "norm" going forward, and I suspect that any company enforcing that is going to find it harder to attract talent (unless they are FAANG companies, in which case they can do what they like and still attract high-quality applicants 😅 ).
From what I've seen in my local area, there are many companies who have really invested in remote work, finding alternative ways to foster creativity and connection in their teams other than "being in the same room". This is purely based on what I hear from my local network, but it sounds to me like these companies are unlikely to go fully back to the old 9-5-office-based work because they've invested in all these alternative strategies and their team values the flexibility.
It's also opened up recruitment for them - for example my old employer used to really struggle to recruit above entry-level positions. There are a lot of tech companies based in Edinburgh, and people get snapped up very quickly! Being able to hire outside of the geographic area has been huge for them.
I guess time will tell, but hopefully some amount of flexibility will be the new normal 😄