I can see many future domestic uses that might need multiple terabytes per sec of speed. Especially everything around AI and machine learning. Imagine your device having instant access to multiple terabytes of a shared global library of machine learning data. Its a bit dystopic but thats another topic.

Another thing you can imagine is being able to play games directly "from the cloud" but processing them on your hardware. Imagine you have an xbox, but don't have any games stored on it. Everything you play is fetched in real time from the server but still processed and computed on your hardware. So you get crisp clear image and visuals but games can now be so realistic that they themselves need 1-2TB of storage to store the whole game. So, with enough internet speed, we wouldn't need to worry about storage space anymore and how big a game is. You just buy the game and click play and play instantly, but still computing the game locally. Or, if you still need to download and store the game, having a game be a 700GB download might be as "casual" as a 5GB game is nowadays (remember when we got shocked that games started to be more than 1-2GB? Now, 80GB is common). And you will be able to download the whole game in a few minutes. Game worlds can be huge and still be downloaded in minutes. Storage is also evolving day by day so 10TB of SSD might actually be kinda cheap in 10 years.

You can also imagine games so complex that they can now comunicate between players huge amounts of data so we could even share the same angle every leaf in a tree is moving to the wind so all players on that server would see the same exact movement of the leaves. The bandwidth is so high that you can actually start to share all of the most insignificant details between a multiplayer world.

You can also imagine Netflix being able to stream 8K 60fps HDR to your phone as easily as nowadays it streams 720p.

Virtual Reality. It needs insane amounts of bandwidth for anything. If you want to share a truly multiplayer VR experience you need all the bandwidth you can get. VR cloud gaming could be a thing since they could now transmit 2x 4K 60fps streams with minimal latency.

These are all casual domestic uses for unlimited bandwidth applications. Don't worry, we will always need more and more bandwidth, because with more bandwidth always comes new tech, and with new tech the need for more bandwidth also increases. Infinite cycle.