I was going to post this in a reply but by the time I was done I thought it was worth posting as my own blog post.
Here is my way of seeing what comes after Web 3.0 based on the past:
Web 1.0 - More localized. Limited by phone lines. The cost of accessing distant information and data (a.k.a "long distance calls") via modem is often prohibitive.
Web 2.0 - The cost of accessing data and information on the other side of Earth is economically feasible by most standards. The cost of using data and information to create a virtual world or worlds through hardware and software is often prohibitive.
Web 3.0 - The cost of using data and information to create virtual worlds through hardware and software becomes economically feasible by most standards. The cost of sending and receiving distant information and data to and from orbiting stations around Earth and off-world colonies is often prohibitive.
Therefore, Web 4.0 is an interplanetary internet. Web 4.0 has to face the challenge of how to deal with the time delay caused by the speed of light. As a global network the speed of light wasn't a huge problem for the majority of its uses. This won't be true for a decentralized internet that extends beyond Earth.