1. Peer to Peer Global Wiki-eque Nature
Users will be able to modify content from all websites. Portions of sites such as ads and low quality content will be filtered and disappear from view. If you see something you don’t like rate it low and if enough other users do the same then your browser or browser plugin will automatically filter it out. It does not matter that the sites themselves might not add these capabilities, they will be maintained in external data distributed among your peers.
It works in the positive vector too. You will be able to view comments attached to sites by your friends. Cool or useful content can be highlighted and shared easily. Relevant links can be added on the fly based on what other users who liked the page you are on also like.
The maintainers of current sites don’t need to ‘upgrade’ to achieve this functionality. It will grow organically whether sites care to embrace it or not.
2. Amazing Collaborative Projects
Open source projects are achieving new levels of interactivity. Look at the success of Wikipedia. Users from around the world are able to contribute to all kinds of amazing projects. The newest internet users are starting to take this for granted, for the next generation it will be a given.
Software is getting as big a boost as anything. Look at github for massive social collaboration. New software is able to reach an increasing number of people; projects can be improved, forked, and maintained long after the original developer has moved on. The greatest ideas will be iterated and improved rapidly and spread throughout. The success of Ruby and Rubygems is a testament to this.