They do not exist in every EU country. Being in a a few countries of 27 member states is no good. This ruling applies everywhere in the EU.
AT&T and Verizon operate in all of the US states. That is what will have to happen.
We will end up with a few operators. Three and other "small" operators will be screwed.
The European mobile market will become one massive oligopoly with high tariffs like in the US.
You can see
here how much the likes of Vodafone will have to expand to cover the EU.
http://www.telegraph.co.uk/finance/...-to-end-mobile-roaming-charges-next-year.html