Obviously he can. Will he? It remains to be seen. The problem isn't that you have to believe in a vast, global conspiracy on the part of almost every human being on the planet to dismiss the idea that Pope Francis identifies with liberal values and the Marxist inspired ideals common to Latin American liberation theologies. The problem is, the Pope himself seems intent on living up to the various rumors.
True, he hasn't changed actual church teaching. But you don't have to. As I explained here some time ago, Catholic apologists made it clear that even if the Church in the Middle Ages tortured the living hell out of people, officially it never taught it was right. According to actual doctrine, the Church was all about turn the other cheek and love your enemies. Just because the church, popes, bishops and church leaders seemed to put their stamp of approval on the torture and killing of those in the Church's way was irrelevant.
If that is true, then it suggests that the Pope doesn't have to change church teaching. He can simply repackage it in a way to conform it to the modern trends of the moment. The teaching itself will remain the same. But how we live it, teach it, breath it, pray it, and follow it on a daily basis will look just like the world around us, much in the same way the Church looked like the world around it in the 13th and 14th centuries.
Like Morpheus might have said to Neo: 'No Neo, I'm not telling you that the Pope is going to change church teaching. I'm telling you that when he is through, he won't have to.' Let's hope that's all unfounded concern and worry. And let's hope that in the coming days, Pope Francis goes out of his way to show how unfounded it is.