Previous reports on the matter indicated that Microsoft might plan to offer Windows 8.1 Update 2 to users through the Windows Store, in order to make it easier for everyone to download it and thus make sure that no installation problems would be experienced.There's also a rumor that Microsoft may make Windows 8.1 Update 2 available for a fee for Windows 8 users who wish to update directly to this release without first having to install Windows 8.1 and Windows 8.1 Update 1. It's believed that people who pay for this might be allowed to get Windows 9 completely free of charge, while everyone else will have to pay for it when it comes out in early 2015. None of this is officially confirmed though.
It's a well-known fact that Windows 8.1 Update caused quite a lot of problems to users who tried to install it, in most cases due to hardware compatibility issues, but Microsoft launched several patches to address the issues and thus make it possible for everyone running Windows 8.1 to deploy it.
Source: Softpedia