portyllo

MHz-POP makes the most sense in cell networks, where an operator (AT&T, T-Mobile,...) wants to acquire a spectrum license in a particular region of the country. Evaluating the MHz-POP makes sense as the price they are willing to pay varies a lot depending on the population density in that region area. In general, cell networks can reuse spectrum more easily (deploy more towers, add more sectors), and they design their network deployment to hit whatever MHz/customer they are targeting (which mostly depends on the technology 3G/4G/5G).

In sat-networks, well, MHz-POP doesn't matter that much, because, generally, every operator is licensed to operate in the whole country. As you mentioned, what really matters is (a) the bandwidth of their license allocation (e.g., Globalstar is 11.5 MHz), and (b) how efficiently can they reuse spectrum:

* how many beams can they land (# satellite x # beams / satellite)?

* how much freedom do they have to chunk bandwidth and allocate it to individual beams based on demand?

* what type of satellite are they using, bent-pipe or regenerative payload?

* how big are these beams?

* can they allocate resources dynamically or is everything fixed?

* how much power does the satellite have? how big are the terminal antennas? what kind of link-budget can they close?

In the end, the MHz/customer they can achieve depends on the answer to all these questions.

A MHz-POP is just bandwidth times population covered by the Geographic Service Area (i.e., where the company is licensed to operate). For example, in the US, they would have 11.5 MHz x 330 M = 3.79 Billion MHz-POP.

No, it will not be possible, no matter what Elon says.

Starlink operates in portions of the Ku and Ka bands that are reserved for Earth-to-space comms, not for space-to-space comms.

Well, look at Oneweb as an example. They have raised 3+ billions, still need more funding and their total system throughout is not that much larger than Viasat-3's,which has a cost of ~1 billion (?). I don't think that Starlink is gonna be significantly (maybe a factor of 0.5x) cheaper in terms of cost per Mbps.

Developing compatible systems would be very expensive. There are very few standards in Space Comms., specially for satellite-to-satellite Comms.

SpaceX satellites cannot handle 1 Tbps each, they can handle 23 Gbps each according to their FCC filling.

Specially now that the satellites have no crosslinks.

It's not true. LEO systems are far more CAPEX intensive than GEO, and neither Starlink, Oneweb, Telesat, or Kuiper will be cheaper than Viasat-3 and will not be able to compete in terms of cost per Gbps.