Can be FUD, but just imagine install sizes with constant 5 GB streaming
That is the wrong way to look at this. A game is just a package of shaders, textures, geometry, audio, texts, code etc. Each level can reuse from the same set of package of textures, geometry, audio, texts, code, etc. Level 1 can still use same textures, geometry etc as Level 20 even though visually they might appear different. Though the storage can load 5GB/s, it will still be loading from the same package of shaders, textures, geometry, audio, texts, code etc. A storage that is capable of more throughput loads from that same package but much faster assuming there is not a bottleneck somewhere. Each second of gameplay is not loading unique data, you would just be unloading and reloading data as needed from the same pool of game package of arbitrary size.
I seriously recommend people watch this GDC talk on data management with games.