Apple obviously writes its own software for the iPhone, but Samsung's phones all run a customized version of Google's open-source Android, and Samsung is so dominant that it could very well split off and start building its own version of Android, just as Amazon did with the Kindle Fire. That would be a huge blow to Google. If the rest of the market can't make money using Android soon, it'll provide a big opening for Microsoft.
Google also has to find a way to limit the influence of wireless carriers on Android. Companies such as AT&T and Verizon are all too happy to load up Android devices with unnecessary crapware and bloatware that ruin the user experience while delaying important software updates.
The animosity between Google and the carriers has gotten so deep that Google's new Nexus 4 flagship device doesn't have an LTE radio; the carriers simply wouldn't cooperate.
That's in stark contrast to the iPhone experience, which is pristine and controlled by Apple from the start. It's a control that irritates power users but offers a sense of support and security to the rest of Apple's millions of customers. There's a happy balance between the two extremes, and Google needs to find it before Android begins to slip away entirely.
These are just five of the many interesting things to look out for in 2013, from the future of TV to the rise of wearable computing. After several years of rapid change, we've all got computers in our pockets. The next few years will be about what we do with them to make our lives better.
Follow us on Twitter @CNNOpinion
Join us on Facebook/CNNOpinion