The next big step in mankind evolution (maybe the ultimate one) is the emergence of a Super Artificial Intelligence. Before that moment other events will happen. Humans have developed magical technology however there are not changes in our biological setup. Even for communicate each other we use EXTREMELY SLOW ways as talking, writing, etc.
Connections brain-machine and brain-machine-brain will:
1.) Boost the speed of information.
2.) Open the door to another level of use of the brain: sharing feelings, instant knowledge or using other humans senses as they were yours. Even every discovery in this field is a huge thing by itself. Can you imagine coming alive again an old experience to your brain, let's say eating a lion, fighting with a cake (or the other way around better), wild sex adventure, etc., or even "import" those experiences from other people?
3.) As a future interface human-AI. I could imagine a scenario where eventually brains are connected each other and also connected to an AI. In this case brains are just like neurons in a new super brain. I guess that new entity will want to explore outside and establish connection with other intelligences. It looks like brain was designed to play with other brains.