What is the cost of the satellite service after two years?

This is the only support document I can locate with information about the SOS service. Use Emergency SOS via satellite on your iPhone - Apple Support

It states that it is free for two years however, does not address a cost structure afterwards. You would need to contact Apple Support to ask them for that information.

To my knowledge, Apple has not announced what the cost will be.

Hello ~ In addition to * lobsterghost1’s* information click on below…

Apple extends Emergency SOS via satellite for an additional free year - Apple

~Katana-San~

Apple has not announced pricing after the free service expires. AAA has announce that it will include the service in their membership for road side assistance.