I'm not particularly interested in the 'sustainability' of the Internet. Google and a couple of other companies that have more money than the Catholic Church can worry about that. I'm interested in my privacy and peace of mind.
I am not going to cry if the commercial ventures on the Internet die. IMHO, the Internet was better back in 1994-5 anyway when it largely was NOT commercial!
I have a web site that I pay for and maintain myself. It's a purely commercial web site, yet it's free and there are no ads: this as it's the front of my company. It's advertising my tour business, and is visited by people that are interested in my tours, and allows them to book tickets to tours. I also add general information on hiking in Hong Kong, which people may use to set out by themselves. It's set up for purely commercial reasons, and I think such commercial sites are by and large a great addition to the Internet. I'm using such sites myself: to find information on products, to order stuff from. The Internet would lose a lot of its value if such commercial sites would all disappear and we would have to resort to calling companies, visiting their shops (which may be the other side of the world) to get a catalogue, etc.
For my business it is a great help to have this site, I sell a lot through it. It makes the whole ticket sales easier as well (very little manual interaction from my side needed). I wouldn't want to do without - people can't find me nor can they easily get the information about my tours that they need to make a decision on whether to join, ticket sales would become cumbersome; basically I'd have to close this part of my business.
What would be great if lots of this "targeted advertising" and collection of personal information goes. So I'm still running AdBlock Plus and Flashblock, and recently installed Self Destruct Cookies - an add-on that destroys cookies moments after you leave the site. Sure you have to re-login all the time, which LastPass makes dead easy, it does take care of most of the tracking across sites by outfits like Google and Facebook. This is just one aspect of the commercialisation of the Internet, something that my commercial use of the network can perfectly do without. I'm even collecting only the most basic information of my clients: name (I don't care if it's their real name - they just have to give me that name when they show up at the start), telephone and e-mail. All I need to be able to contact them, and for them to claim their place on the tour.