THE problem with Comet, according to Pete Mowforth, chief executive of Glasgow-based e-commerce specialist Indez, is that it is an intermediary.

It is a channel through which manufacturers sell goods to consumers. These channels are having to adapt to a world where people are increasingly buying things with a few strokes of their phone screen. In many cases, there is no need for them at all.

"I spent an afternoon this week with whisky manufacturers," he says. "Historically, they did everything through wholesalers. But if they sell directly through the internet, they can cut them out and make more profit. E-commerce removes the need for intermediaries. Comet is an intermediary. It doesn't make anything."

The proportion of all retail that now happens through the web is just short of 9%, according to the latest figures from the Office of National Statistics. That £26 billion a year is still obviously relatively small overall, but it is triple the proportion of the mid-2000s. It is also severely held back by the fact that food sales online are just 3%, yet food comprises over one-third of all retailing.

Tesco sees online food shopping as a huge market. It has been pioneering "dark stores", which customers visit not to shop in but to collect goods they have bought online. Tesco has four such stores in London and is looking at other cities with a view to opening more.

Professor Leigh Sparks, of Stirling University's Institute for Retail Studies, believes this sort of drive-through model will catch on now that most people are carrying hand-held computers around in their pockets.

"Look at Argos, who are saying there will be much more digital than catalogue retail in future. As it stands, 39% of Argos's sales are now done online and about 80% of those are picked up through stores, not through home delivery. It's about click and collect."

While Argos implements this model, the logic is that it needs fewer shops. Hence it announced only days ago that it will be closing or relocating 75 of its 700 UK/Irish stores in the coming months. If you are selling fewer items in your stores, it makes sense not to spend as much keeping them open. And as online delivery times move from days to hours, shops lose the advantage of instant gratification that has helped keep them important until now. Just like the logic of online music is fewer physical albums, the logic of online shopping is fewer physical stores.

It is not as if high streets are at their best, anyway. Earlier in the autumn, the Scottish Government appointed Edinburgh architect Malcolm Fraser to head a review into the sector. It aims to look at Scotland's 20,000 empty shops and offices and come up with proposals for how to bring them back to life.

Part of the problem is out-of-town shopping, although Sparks cautions against over-simplifying the issue. He apportions shares of the blame to everything from certain local authorities relocating out-of-town centres to airport retail opportunities tempting shops to move there instead. Equally, many out-of-town developments are also struggling, undermined by better, brighter ones that have opened down the road.

Sparks points to a feeling that each next generation of shopping mall is an improvement on the ones that went before. But the problem is what you do with the old ones.

"There's been a race for space," he says. "Retailers wanted to use it, property developers agreed to build it, but consumers have not been going to them in quite the same way."

For Pete Mowforth of Indez, these are symptoms of a deeper problem with traditional shopping, which he claims has already passed a tipping point.

He says: "Ultimately, people are going to buy online because it's cheaper and more convenient. It's a self-fulfilling prophecy. The more this happens, the less they sell in stores, the greater the cost per unit by selling through stores. If they sell 20% less than before, if you do the numbers they almost have to double their margin to get the same cost per unit. There's going to be a tsunami of change and very few people are getting their heads around it. In 10 years, something like two-thirds or three-quarters of shopping will be online."

Not everyone agrees change will come so quickly. Forrester Research is forecasting that 17% of shopping will be online by 2016. But as click and collect and innovations such as online virtual changing rooms take off, most observers agree that online will maintain the 10%-plus growth it is currently seeing for years to come.

Mowforth envisages a world where high streets are reduced to social businesses like pubs and restaurants, plus a few other exceptions like small-transaction outlets selling goods that are not worth the distribution cost, or personal services shops like barbers that need physical contact with the buyer. He believes that city planners have not begun to think about what such profound changes will mean to our shopping areas. This might be the perfect opportunity for Malcolm Fraser's review to start them moving in the right direction.