It’s currently roughly $1miilion to launch a Starlink satellite on the Falcon 9 (~$60million / 60 satellites) at market prices. I’m sure it costs SpaceX less than this, but market prices should be used for any spun-off company. Just to launch a 15000 a bird constellation would be somewhere in the neighborhood of $15 Billion. I believe each satellite has a lifespan around 5 years at the very low orbit they have specified meaning they would have to spend $3 Billion a year in launch costs just to maintain the 15000. Add more satellites and the cost goes up. This doesn’t include any other costs such as: operation, design, sales, satellite hardware, etc.
I’m not sure how big the market really is to fund these types of expenses. I’ve seen things tossed around like $50 Billion potential revenue, but no info how these figures were calculated.
I would love to see this thing pan out, but it is a very risky endeavor even with the head start. The satellite industry is littered with failed companies that couldn’t achieve the projected revenue. And let’s not forget Jeff Bezos is hell bent on launching his own system using Blue Origin. This adds additional risk in the form of probable competitors forcing revenue down.