I just think that it's an uneasy "let's keep our eyes closed" arrangement to begin with. If the Telcos want to open their eyes instead, they might find they have a lot more to lose than to gain. Ditching Net Neutrality will cost them a whole lot more than it will gain them, as soon as content providers realise that actually, the providers should be paying them, not the other way around.
I mean, if Telefonica wants to block access to youtube, why should Google stop them? Fine. Block it. And lose 80% of your customers overnight. If Google wanted to play this game, they should be asking Telefonica to pay them money.
It's not a long step from this to having bloggers, newspapers, etc, organise in collectives that can charge telcos for "access to every newspaper on the web" or "every blog on the web".