Obviously, we're not talking about datacenter-levels of oversubscription. You'd be talking consumer-levels of oversubscription. Yes, this would be an oversubscribed gigabit link, really a whole lot like DSL, except that instead of 10Mbps max, you get 1000Mbps max, and because the physical plant is so much cleaner, you could do much better QoS.

I mean, a shitty datacenter-level gige link delivered to a data center where the provider has a POP (if you are only buying a single gigabit; this stuff gets way cheaper as you buy in bulk) is about $750/month. Less if you know people, more if you sound like you have money when you call the sales rep; maybe 3x to 5x that if you want a big name. ($750 is what the he.net guys will quote you straight off.)

You would, of course, put 50 or 100 folks on that gigE link. Would this mean that everyone would get 1-2Mbps? not unless everyone was running the link full-throttle all the time.

This is... not dissimilar to the over-subscription ratios on DSL. And it mostly works okay, because it's hard to run a gigE link full-throttle all the time. And like I said, having clean physical plant (where you know the actual maximum throughput of a line, rather than the DSL bullshit, where it's loss depends on the phase of the moon and last time it rained) makes doing QoS way easier.

In many ways, this would be a lot like DSL, in that you'd have a 'star' topology within the building, each customer having a full-duplex connection to your pop within the building, then 'oversubscribe' according to cost concerns at the network edge.