We can't compute credible figures at this point because a lot of the technical information is proprietary and the business model isn't known. I don't believe Elon has committed to any specific bandwidth; searching yields claims of "up to" 1 Gbps.
Given the rates cited here[1] (20 Gbps/satellite) I seriously doubt that 1 Gbps is going to be offered at a price level that allows it to be widespread. More likely we'll see service offered in the 10s of Mbps.
So the best we may achieve is some napkin level estimates. Let us assume 100 Mbps as a realistic subscriber rate. 12000 satellites[2] * 20 Gbps/satellite * 100/1 over-subscription (typical, see here[2]) / 100 Mbps = 240 million theoretical subscribers.
Obviously every figure here is open to endless dispute, but we're in the right order of magnitude. I believe this is the scale Elon is thinking at; he's trying to fund interplanetary space travel with this. In any case there will need to be a couple mountains worth of transceivers for the plan to work, and making fixed function electronics at that scale is typically highly cost effective.
I'm on a small island in the Pacific. If I can get 100 Mbps, by any means, whatever the latency, it will competitive. Right now I pay for 25, the two ISPs on island swear they're building out to 50, and I average 15 down and 1.3 up. my latency sits around 250-300 ms to North America and 150-250 to Asia.
Your math left out the biggest factor, which is useable bandwidth. Most satellites will be over water at any given time, so the number of users will be far less. Any you're talking about full build out, which is a decade away. Internet consumption has been growing nearly exponentially.
That's a great point. Figure 80% of the Earth is ocean, 240e6 * 0.2 = 48 million subscribers. Still large enough to justify, for instance, the custom ASICs necessary to achieve a low cost phased array.
Given the rates cited here[1] (20 Gbps/satellite) I seriously doubt that 1 Gbps is going to be offered at a price level that allows it to be widespread. More likely we'll see service offered in the 10s of Mbps.
So the best we may achieve is some napkin level estimates. Let us assume 100 Mbps as a realistic subscriber rate. 12000 satellites[2] * 20 Gbps/satellite * 100/1 over-subscription (typical, see here[2]) / 100 Mbps = 240 million theoretical subscribers.
Obviously every figure here is open to endless dispute, but we're in the right order of magnitude. I believe this is the scale Elon is thinking at; he's trying to fund interplanetary space travel with this. In any case there will need to be a couple mountains worth of transceivers for the plan to work, and making fixed function electronics at that scale is typically highly cost effective.
[1] https://www.reddit.com/r/Starlink/comments/7xzkl5/starlink_s...
[2] https://en.wikipedia.org/wiki/Starlink_(satellite_constellat...
[3] http://www.ctcnet.us/wp-content/uploads/2014/02/CTC-Connecti... "Cable modem and DSL providers often have a 100:1 or greater oversubscription ratio for residential users and a 50:1 ratio for business users."