There are political avenues to explore. Just as Microsoft was hit hard by a number of anti-monopolistic EU decisions regarding Internet Explorer, Apple in particular could be the target of an action in that space.
But this is the kind of thing that requires citizen action. Also, expecting the EU commission to be the only political consumer protection for multinational corporations is not ideal, there ought to be more actions on the American side as well.
Until then, I highly doubt that there will be any hope of breaking the duopoly, at least until Google's or Apple's core business model starts failing them, which is unlikely to occur within twenty years.
From an economical perspective, monopolies are great for companies and for the country's GDP, but they tend to cause lower standards of living, because of the loss of competition.