Bitcoin blockchain doesn't need internet but it needs a stable network. We are using the internet for Bitcoin as it is the best network solution today. It's possible that one day Bitcoin will have it's own network with several connection possibilities and that the internet will be a side network that is connected to that main network.
I see, it's quite ironic to say it doesn't need an internet but a stable network. In the first place, network will run through the world because of Internet, and Internet is the network itself. I don't think there's any more reason to consider having a bitcoin network without an internet as it is the fundamental requirement to connect the people around the world. If we are to think of possible ways, was it infrared? Microwave? no, nothing can be more suitable aside from the internet.