In my time, I could see three Internet giant. They are described below from my point of view.
First Giant: Yahoo!When Yahoo! came, there were some scattered online directories, email services and messenger services. They defeated them by making all services together. They built a hub of directories and offered free limited space Email and Messenger service to grab interest of huge number of people.
Second Giant: Google
At time when google was founded, they came with different idea of Internet Directory. They made a smart search engine, where people can easily search what he needs from Internet. And google became the best alternative of directories. They made their business by inventing smart Internet Advertising Network. Then, they are expanding their business by acquisition of new Ideas.
Third Giant: Facebook
Facebook came with the idea "Connectivity". Not on-demand connectivity as Email or messenger, they made almost permanent connectivity media. A new era began, the era of "Social Media". They could put the people of same interest connected.
There were more other big companies exist, but these three I have described, they could grab user's interest by being the hub for getting services of other companies. At yahoo's time, people came to Yahoo, and Yahoo led them to the service (whether it is their own or 3rd party) they needed. Google make it easier to find anything over Internet and facebook made a platform for users to cooperate themselves to get or do anything.
Once directories were the center, then search engines led and now it's time of social media. But, none of them could substitute each other. Importance of them couldn't be reduced. Each of them are being used by users parallel manner. So, it is obvious that, if anything become the hub of these giants, then it will be the next giant. May be Sumazi could realize this thing and trying to make it gradually. I have seen their beta version, it is helping the user to be introduced with persons related to his interest of a particular instance of time with particular type of problems. But, it is not enough.
The next giant will be able to establish communication between users and information, persons and services for a particular instance of time and situation. People will not have to think about keywords for finding his required information from web, and he will just get the result based on his activities.