I'm not sure if you are using FiOS as a synonym for FTTH. If so, you might be interested to know I live somewhere with FTTH that is reasonably low-density (~25-30 people per sq km). I think Starlink will be a very serious consideration here.

When I say FiOS, I'm thinking gigabit+ FTTH/FTTD (I'm not 100% sure of the difference). Given that you quoted people per sq km (about 70-84 people per sq. mile), you're probably not in the US. In the US, it's hard to get fiber outside of areas with the high density I'm quoting (at least in my experience).

But yes, that density seems fine for Starlink (although maybe it isn't in the end, who knows yet.)

My understanding is that StarLink is aiming for 100M un-guaranteed in beta. So that's considerably below gigabit.

But I also know that most households with FTTH around here use considerably less than 50M.

So perhaps you meant that gigabit internet kills Starlink. FTTH has some advantages over Starlink. But Starlink also has advantages over FTTH. If you need more than 100M, Starlink is not in the game yet. But if you want some leverage with the local monopoly and have typical usage...

Or, if you snowbird (common case here) and want the same provider on the border of Canada and the border of Mexico...

The total aggregate bandwidth Starlink will have when their entire constellation of satellites is deployed and the number of satellites that will be visible at a given location at a given time place an upper limit on the number of customers they can have even with overselling bandwidth.

In the US their plans are to be able to support something like 5 million customers. That's less than 5% of the number of customers Comcast has.

It really is by design meant for people in areas that do not have terrestrial broadband.

This is exactly right!

I think that 5M is a high number (at least with the current number of satellites and their architecture), specially if they do not apply data caps.

I would say that 1M customers in the US is a more reasonable figure. If they hit these number, I expect the performance to degrade significantly.

I thought something like 20% of America did not have terrestrial broadband. At 5 million this is a giant change, but not as universal as I originally thought.

I wasn't referring to the speed (although obviously fiber has higher speed and reliability, and that will likely never change). I was referring to the fact that it seems like if you have the population density (in the US, at least in my knowledge) to justify a local ISP rolling out fiber to homes, you have a population density that will oversubscribe even the completed Starlink constellation (locally). Starlink just is never going to work in NYC or SF or areas with significantly less density there. Although it may work for a lucky few who manage to enroll before the area is full and locked down.

Some low-density parts of the US have fiber as well thanks to programs like https://www.usda.gov/reconnect

Sure, but it's some for a reason. It's a generality. So is "if you're shopping in Goodwill, you're not driving a Ferrari". Obviously, the recently broke, extremely thrifty, people looking for a collectable or to reclaim something accidentally donated are exceptions.

Maybe that program has covered more than enough people to make it worth talking about, but I didn't see anything like that.