Thomas would use that Maths degree of his, probably work for Interspace or some similar corporation.
Magnus would retire again, since he only came out of it to help clean up Bretonia and protect the people because of the war.
Roger would probably join the Colonial government in some way, or have a quiet retirement on Pecos or Yuma.
Susan would probably end up on Yuma helping her father run the colonisation effort there. Liam is never in space anyway.
Michael would probably end up in a bar somewhere, alongside Sam.
Dennis would likely take a desk or storehouse foreman job for IMG, spend more time with his wife Claire and raise their second child when it's born.
Iain I'm not so sure about. He's outlawed in his home of Bretonia, and made a similar name for himself in Rheinland. Might end up living the socialist dream with the Coalition.
Gauss would head out to the Omicrons again, buddy up with the Zoners again.