Businesses of all shapes, sizes and purpose are migrating by the millions to cloud computing solutions like Google Apps and Dropbox. Their reasons are not complicated - easy to use, full featured, reliable, flexible, empowering and inexpensive.
On-premises vendors have been sitting pretty for some time. Imagine - you are able to sell a product over and over again yet it costs you next to nothing to duplicate, you make 90% profit margins on support yet customer personnel actually support and maintain the systems, you collect large upfront payments AND charge annual fees. This business model created our world's richest man. In this paradigm the vendor holds nearly all of the leverage.
Cloud Computing upsets this balance of power, creating a trillion dollar opportunity.