Mark My Words
It's going to go wrong. Terribly, terribly wrong. Giving ISPs more of a leverage than they already have to squeeze the life out of small businesses and competitors ... it's a mistake. If an ISP/whatever can buy and actively use such technology and feel good about it, there's something wrong with its management. There has to be, because they would do better to advocate improving their networks and the networks of those around them for everyone's benefit and to support the use of standards to ease the problems of end-to-end QoS (I know, like a lot of the net, there will be those who abuse that too, but we have to think of the people for whom the net is built and they make up most of it, so we just improve implementations to support a more secure design and thereby putting the issue in the hands of the people). On the other hand, the technology companies are making a handsome profit from what they know is a lucrative market and a controvertial issue while happily skirting around the touchy issues involved (don't you just love the bit about tracking individual users?).
Tip: ISPs that treat their customers like third-rate citizens *do not* get my vote. If I find you traffic shaping/blocking/limiting or transparent proxying without prominent notice to would-be customers (no, terms and conditions are not enough - you must publish the fact that you manage your resources using these methods and make your customers understand that you think it's a good idea for their sakes), I shall at once condemn you and your customers to my best sneer. I will also make no uncertain remarks about the issue if I get someone asking me what ISP to go for. Although I don't like it, I'm less worried about ISPs who call their service plans "Unlimited" providing there is no enforceable cap (some do, some don't). I still recommend you don't call your plan unlimited though unless you're damned sure every one of your customers - even the greedy bastards who're on and loading all the time and who don't keep much-needed information/downloads/etc offline - will not reach any cap, either policy or technical.