The shops themselves were never the problem
The problem with the DSGi shops has always been that they target people who don't really know what they need, never mind what they should be buying, and thus have them staffed with people who don't know much (if anything) about what they're selling. It's compounded by their nonsensical warranty gubbins.
There will always be a market for a brick & mortar electronics store with up-to-date products in stock and knowledgeable staff - how much profit can be made from such a store, and how viable it is as an international chain, is another question entirely. (Compare Richer Sounds to Dixons and you'll see what I mean).