I'd like to see some direct information on what was actually said by the ISPs and where it's come from. This article is a lot of speculation based on a statement that they've said something and then an existing service offered by one ISP. Clearly they're not going to block games and dating sites which this service does so it's not clear why we should assume that it's any sort of useful template for what's proposed. I…
Why won't they block games or dating sites?
That Talk-Talk product was put in place in response to earlier requests by MPs to "protect children", which is why mobile content tends to have filters now.
It seems that filter is as good a model as anything else for what the filter will be.