My guess is it'll end up as opt-in, but cookie based and with no network level opt out, meaning browsing data will still be acquired. The fact that users can avoid having the targeted ads will make it harder for those of us who object to explain what it is we still object to. The weasels at phorm can doubtless find ways to turn the data into cash, even without directly targeted ads,
If people stop using adverts to look at items then they will stop using this method. No orders from the targeted adverts then tose advertising wil cease to pay to advertise. Never us an advernt from now on use only links from reputable searches or direct links to such as kodak comet etc.
Money talks if thye earn nothing they will not continue plus you could always object by using your wallet and move to an ISP that is not using Phorm or equipment like phorm. The servers Phorm are using are not within BT's network all 2 racks of them.
Targeted advertising is a generalisation, most of the adverts on ISPreview are targeted to the consumer ISP audience. That does not mean they're bad - advertising itself is not bad, without it we wouldn't exist. It's important to reference the difference between the advert and how information is gained/tracked, with the latter being what concerns people about Phorm.