Some small businesses struggle, and some don't. Economies of scale give a lower unit price and probably some greater freedom of movement for development, but big companies go under too - eg MFI, Woolies and so on.
Classical economics argues that the price mechanism is the determining factor, but clearly other things are at play. Exclusivity, or a 'nice' shopping experience might offer 'added value'
Nevertheless, the sum of the product has to have a large enough market to sustain the outlet - indeed, c'est la vie.
The ?1,000,000 question is, though, what kind and what format of business will now survive in Honor Oak Park? What is the strength of potential market in HOP? If shopping is reducing to simply acquisition of stuff, then ordering by internet and home delivery is the thing and shops, as we know them, will go. However, hairdressers, and I guess beauty therapy, will still require people to do a hands-on job. The same with cafes and bars. Services still require people, so these might be the kinds of shops for the future. Books, and toiletries, are probably most easily bought via the internet - I know I do.
The other exceptions are places like Green and Blue in East Dulwich, which combines a thoughtful and different wine merchant with a small deli and bar. Three businesses each in symbiosis with the other. The wine merchant aspect also has a website for ordering and delivery. Perhaps it is having this multi-line, multi-media approach which is the way forward?