AT&T has a problem on its hands. It's big, but is it big enough? If you're a CEO of a major corporation the answer to that question is always "no." However, the carrier has difficulty expanding on the home front. An overwhelming majority of U.S. citizens have phones with one carrier or another, so there's very little wiggle room to grab new customers. And gaining in market share when you (and all your competitors!) are dead set on locking people into two-year contracts is very difficult. In short, growth isn't much of an option outside acquisitions, and those haven't gone so well.
Which is why it makes some sense when the WSJ reports that AT&T is looking to invest in European markets. According to "people familiar with the carrier's thinking" (what?), the company is hoping to find a market where it can invest in new infrastructure and play with new pricing strategies. The former sounds like a great idea. Europe historically has not been as aggressive about 4G rollouts as the U.S., so if LTE could be a distinguishing factor of a new venture, attracting customers would be easy.
The second part, though, rolling out "more lucrative" pricing plans could be a much more interesting turn of events. European markets have a higher tendency to buy phones off contract than U.S. customers. Would the carrier try to change this? Maybe pursue a subsidized model that would be attractive across the pond? Or would it simply attempt to shift the focus from minutes and texting (as it is now) to a data-driven model which is by far the big push for monetization today? It's much better for mobile operators' bottom lines if you're using more data, and on more devices. We might see an aggressive shift towards shared data plans and connected devices.
Ultimately, though, AT&T still has to decide if it's even worth it. Getting started in Europe means they need to find a company to partner with and that won't be an easy task. There is also a whole different set of regulations it would need to navigate, and of course merging with any carrier will require billions in investment, not to mention be subject to regulatory scrutiny.
Still, AT&T's CEO sees it as "inevitable" that the company will expand to international markets in order to grow. Well, sure. Just ask Softbank. It is, after all, in a carrier's nature to want to be number one.