This will determine how many customers they need to stay afloat.
The second key question is, are there enough customers that can pay $100 per month for service?
If not, Starlink will crumble.
You have to be fairly affluent to be able to afford $1200 per year for Internet service. If you can afford it, a lot of people would like to sell you terrestrial service for less.
This is of course a failure to regulate the telecommunication giants, which get fat and rich in the big cities, but are not good at connecting remote locations (this doesn't earn them money).
On the other side, Starlink was very helpful in setting up emergency WLAN hotspots in the disaster area of the recent floodings.
I really liked that, it was a good illustration of how global orbital coverage can improve lives even in rich countries.
That is what I expect in poorer countries to happen. Starlink may claim that one terminal is meant for one household only, but they will silently tolerate connection sharing as long as it gives them penetration.
And third world metropolises aren't exactly penetrated by optic networks. So the alternative is probably an overloaded 4G network.
If there is some real movement of people in office jobs now working 100% remotely moving to the countryside I can see how Starlink would be a good proposal. It's a small increase in internet costs with a much lower cost of living than in a city.