I think those 50/100/etc. markets are too small to inspire the kind of innovation I'm talking about.

One example that keeps coming to mind is "real" virtual reality (including next-generation MMORPGs and tele-presence stuff). Consider the bandwidth requirements of a world whose physics are malleable: in-world chemistry, in-world shaping of novel materials, in-world machines that actually work in-world or that function by means of realtime-modifiable embedded scripting, etc. All that state would have to be synchronized across millions of clients in near-realtime, requiring things like vastly distributed P2P "rumor mill" replication protocols.

You can do that with Google Fiber grade Internet access. You can't do that with what we have now.