As we all know there is no competition between the prices from the high street shop and the internet, couple this with the ease in which you can buy things on the net, opposed to going into town / city... pay for parking, fuel, or god forbid public transport.. the net is going to win everytime. Shops that have a presence on the net and high street, probably sustain the high street shop by using the net profits.
Dixons was a very early adopter to this, closing all its shops many years ago and being soley an online business (they were part of pcworld / currys group then) but now are even conglomerated into Currys online website too... It seems even keeping the brand seperate is too costly these days.
Where's it all going?, as others have said... the high street will (most are almost there) become ghost towns... charity shops / banks etc. It's a shame for the specialist shops, as there are some very knowledgable independant sellers out there that can assist us in a purchase far more quickly and efficiently than trawling through endless online forum posts about a topic e.g. Camera / Telescope purchase.