I hope that something is done with town centres, as otherwise we will all end up as isolated as we have been in lockdown.
If more people continue to work from home as predicted, and if leisure activities continue to be curtailed, town and city centres will become ghost towns. Retail is on the way out, other than for convenience items and perishables - growing numbers of people do most of their shopping online.
I think we need to see what happens with the virus. If we reach a point where it is possible to socialise again, then I think having offices converted to living space is a good idea, and shops can become spaces for leisure- eateries, arts venues, sport centres etc. As long as we have to keep distant from one another though, nobody is going to invest.
I think we need to move away from the idea that anything is built around the expectation that people will use cars though. We need to discourage single use of cars and invest in safe, cheap and clean public transport, and this would be a good opportunity to do so.