10 gig to the home costs between $4/month (efficient high volume) and $10/month more than 1 gig GPON, I estimate. Respected analyst Julie Kunstler accuses America of dozing while the Sony & KDDI are now selling 10 gig service for less than $100/month. (Fierce) If anyone wants to buy 10 gig at $100, KDDI would net a little more than if they were selling a gig for $75.The equipment and bandwidth for 10 gig are now cheap enough that it's affordable anywhere there is fiber and a good use for the speed.
I very rarely wish I had more than the 100 meg down I have although a better upstream would be very welcome. (Jennie does video.) 10 gig is about enough to serve every apartment in Jennie's 20 story building. It's enough for 30 4K camera raw outputs or about 600 4K video streams.
Adelaide has a more practical plan: The city is building 10 gig to 1,000 buildings in the central business district and major commercial strips. They expect to finish in two years. I'd bet 95+% of Adelaide businesses would rarely draw more than 1 gig, although that could change in the future. However, the cost to build to 10 gig is low enough that it pays off even at a low take rate.
It's a smart move for Adelaide and I'd recommend it to other cities with commercial buildings without fiber. It pays off directly if the high speeds draw even a handful of businesses. Unlike Smart City manifestos, the high speeds for businesses are more than pr.