Of course, when they first started censoring CP, plenty went, "Well, yes, it's abhorrent, but what about the slippery slope?", and got shouted down by our government, the press, and peers, who all said words to the effect of "Don't be ridiculous, you're hysterical, what are you, a pedophile?".
Even now, as we gracelessly tumble down the well-greased-incline, they will merrily argue that there is no slippery slope.
As to regulation, there already is, and it actively encourages ISPs to censor.