It seems to me that more and more desktop applications are custom web browsers, receiving content from the web, but displaying it in their own frame, instead of the frame provided by FireFox or Internet Explorer, since those frames are too generic and don't provide all the required features to satisfy specific business requirements.
The Cloud is ubiquitous but standard web browsers provide a very limited view on the wealth of data it makes available. Mobile phones and tablets could be seen to be custom web browsers too, while here's a nice example of a custom web browser from Sweden, which could be seen as an accounting-oriented web browser:
(More info about the above: Björn Lundén Information AB.)
Web browsers, in the sense of generic web browsers such as FireFox and Internet Explorer, are, after all, desktop applications too. But for many corporate requirements, these web browsers are insufficient while, conversely, being too heavyweight for consumers. Web browsers, as we know them, are being crowded out by the alternatives, either because the compact size of mobile phones and tablets make them increasingly attractive to consumers or because the functionality they provide is simply too generic to be useful for corporate applications.
As Jonathan L. Zittrain puts it in The Future of the Internet — And How to Stop It, “It is a mistake to think of the Web browser as the apex of the PC’s evolution.”