As it turns out it is possible. According to analyst Benedict Evans (via AppleInsider), it seems that the total amount of sales of iOS devices on an annual basis has actually caught up to that of Windows devices sold. We should point out that this is on an annual basis and it isn’t to say that there are as many iOS devices as there are Windows.
However the fact that iOS has caught up is certainly saying a lot about the market at the moment, which is that smartphones and tablets are starting to become the more preferred method of computing, or at least a viable alternative. As you can see in the graph above, it shows Windows PC sales more or less stagnating, while iOS devices continue to rise over the years.
As for Android, thanks to the various OEMs that help populate the market, Android had long surpassed the number of Windows PCs sold long ago, like back in March of 2012. Will smartphones and tablets eventually overtake PCs? It’s hard to say since both platforms offer different functionality and features, but we wouldn’t be surprised if that were to happen one day.