content: The only thing we want from Mars is information about it.  It makes no economic sense to send resources back from Mars. The relationship will always be us sending them tech products they need (for our life times and our children's, at any rate). Also, no one even wants to live at the south or north poles because life is too inconvenient. People on Mars would never cut off contact, because they want resupplies, a ticket home, and media.