I posted this yesterday, but Jerry doesn't own the Dallas Cowboys for the money. Sure, the team makes millions of dollars, but its sale value at an auction would be several times higher than its "book value" by profits and losses. So if it was strictly a business decision, Jerry would have sold the Cowboys a while ago and reinvested that money in warehouse space or ag land or something.
What rich people really buy with sports teams, is attention from the general public. There's hundreds of billionaires out there who you've never heard of... but I bet you know most of the ones who own NFL teams. People talk about them, right? That drive for attention is what fuels Jerry, and that's something he can't buy into again if he liquidates the Cowboys. So he'll never do it, he's riding this show out.
I don't think Stephen is as ego driven as his dad, but it's not like he needs to sell the Cowboys for money. He'll be set for life either way. So the choice for him is either fame and attention and one yacht, or public obscurity and two yachts. Might as well be famous and play GM.
He'll keep the Cowboys in the family for another couple decades.... the real question is if he'll still keep trying to be a Football Guy after his dad is gone.