Wait, wait, wait. You've made a number of unwarranted assumptions on this thread. How do you know iPhone 5 sales are slowing? By all public accounts, iPhone sales are just fine and I don't think Apple breaks down iPhone sales by version. What the news releases have said is that they cut a certain component's orders for this coming quarter from a particular supplier. But that could mean MANY things, only one of which is that sales are slowing. There is nothing in their most recent earnings release to suggest that sales have been slowing at all - in fact, it's the opposite.
You mention elsewhere that iPhone 5 sales are less than projections. OK, whose? Some random analyst's? This matters immensely, if you weren't aware.
Next, for Apple to beat Samsung out in Q4 in total mobile phone sales (not just smartphone sales) is absolutely incredible whether it's for just one quarter or for the whole year. We're talking about a company, Apple, which only has THREE phone models for sale at the moment. The 4, 4S and 5. And they're not even available for sale on every major carrier. Contrast that with Samsung which has probably north of 100 different devices, many of which are free or close to free and available and on just about every carrier in the country. If you don't see how incredible it is that Apple is still winning the battle of pure sales numbers, I don't know what else to say to you.
And finally, I think the premise of your question is flawed. Apple doesn't need to reclaim marketshare because marketshare is probably the least important of the key indicators. Apple's winning by a huge margin in terms of its share of the industry's profits. We're also seeing much higher mobile browser usage rates from iOS devices compared to Android devices. This makes sense because, again, most people who get Android phones probably don't even know they have an Android phone and probably don't use their phones much differently than their old feature phones. So as you can see, pure marketshare numbers are not necessarily very significant.