I’ve got news for you about Earth-based networking gear. You don’t just install it and forget about it forever - you replace and upgrade, almost continuously, and lifespans are frequently significantly less than five years.
Tell that to your local telco carrier. I bet my ass they have network equipment runnning with zero updates for well over a decade.
Of course, any system will need maintenance. My point was that you need the capacity to do the maintenance and you have to be able to do it cost effectively. That means in the case of Starlink it might actually be important to have Starship available because only this way they have the necessary capacity or cost effectiveness to maintain the constellation while using Falcons might not be good enough. I also say might, I of course don't know, I was just addressing the question why availability of Starship might be a relevant factor.
A 1000Gbps cable laid down in the ground will be able to support 1000Gbps even 50 years from now provided that it doesn't get truncated by accident or Earthquake
a cable is pretty useless without all of the other hardware
That "cable laid down" is vacuum of the space in this situation. It's not going to disappear.