I think that the important thing is that there is a town centre. Whether it is sustained by retail or not doesn't really matter to me, although I do realise that not everyone shops online. I virtually never buy from actual shops, but I think it's important that there is somewhere for people to have reason to go, otherwise we would all end up stuck in our houses, and there would be no difference between living in a city, a town or a village - we would lose any sort of choice of lifestyle, or it would be reduced, anyway.
Where I live the high street is doing ok, but it is mainly middle-end clothing shops, like Seasalt and Hobbs (what my daughter calls 'clothes for menopausal women?), jewellers, hairdressers and health food shops that offer spurious-looking treatments for weight loss and skin complaints. We have the usual chains, such as M&S, Boots and WH Smiths, and lots of cafes. The town is the sort of place that people visit though, so I suspect the cafes get most of their trade from that. There are restaurants too, but lately several of them are closed on Mondays, which suggests that they might be struggling. There is nowhere for young people to buy clothes, and men have a choice between the tiny department in M&S, Fat Face and Mountain Warehouse. We have at least half a dozen antique shops, but there is nowhere to buy a kettle or ironing board since Woolies closed. I assume that this is because young people shop exclusively online, and it is easier to get household items delivered than carry them about with your shopping. When we moved here there was a Currys (or Dixons, can't remember) and an independent shop selling radios and TVs. They are both long gone, as are the wool shops and little craft shops - most have given way to cafes.
I think that town councils have to come to terms with the fact that spending patterns have changed, and retail is not going to bring in the money any more. If they have any vision, they should be looking at what will bring people together in social spaces, even if they are not spending a lot of money. Music venues or theatres, bowling and the sort of thing that young people can do, independent cinemas - all of those things would bring people to the town centre and encourage a sense of community. The space above retail outlets could become flats, so people could live in the town centre instead of on peripheral housing estates.
The impact will be greater than clinging to what retail they can get. Bringing people into towns would help tourism, reduce loneliness, and give them character that many have lost because of all the chainstores that make one high street much the same as another.