There can be an unlimited no. of connections (or peers). Remember the bittorrent days, where you could seed to and download files from many peers simultaneously? You can do the same with data streams, f.ex. video and audio. Try Keet if you want to see a practical example.

We don’t need data centres to share files, chat, do video calls, live streaming, etc.

If I’m having a video meeting p2p instead of microsoft teams running in the cloud, that would reduce power consumption, not increase it.

How about reducing our dependence on data centres by using software that is more peer to peer and local first etc?

Of course some data centres have legitimate use cases, such as big data analysis on weather and climate data etc, but building huge data centres for social media and running everything in the cloud is silly from an environmental perspective