TLDR: The truth that went unspoken until the finale was “is a succession plan really just for one generation?”.

The mark of a good finale is revealing a new piece of information that shines new light on the same story and reveals character motivations that were hidden beneath the surface the whole time. I think we got that with the finale last night. I think so much emphasis was placed on Logan's corporate Succession plan through this series that we didn't realize how important Logan's genetic "succession" weighed on his mind and colored the narrative between the lines.

First off, all the kids achieve complete self awareness here at the end. Kendall keeps firing off lines that cut so close to the truth it feels like the audience POV:

"Maybe that is why you're better adjusted and I'm just a fake business pyscho"

"I'm a specific cog that only fits in this one machine"

"If you don't let me do this I might be dead"

Roman reaches full self awareness too -- not only is he bullshit and was never a proper candidate, but Kendall probably wasn't either. And honestly, Logan was right about the three of them not being serious people. Logan may not have gave off "deep longing to be a grandpa" vibes, but I think Roman saw that it WAS a big deal and that is why he calls it out right at this crucial moment. The subtext is a lot to unpack. Logan, a "good old boy", has a bi-racial adopted granddaughter and a grandson born through invitro that doesn't share his genes. He puts his hands on Iverson. He has that odd "fake poison" dinner gag with him. Deep down, he closed the door on the thought of Kendall carrying on his genetic legacy. Another reason why Tom has so much good will and leverage in his eyes -- he is his key to protecting the "Roy" legacy.

I think there is a case to be made that Logan crossed out Ken's name when he fully threw his lot behind Tom. It even tracks with him adding "Greg?" at the same time as the cross-off, if you view his decisions through that lens, Greg being the only other player with blood relation to Logan. Also recall the background plot of Logan trying to eat foods that boosted his sperm count so he could make a baby with Kerri. This WAS important to Logan, it was just never made that explicit. The truth that went unspoken until the finale was “is a succession plan really just for one generation?”.

Shiv knew that by keeping the baby, she would effectively be delivering her father the "real" grandbaby he expected, and this is why her story is just as much a tragedy as Kendall's. She is confused about being a mother, yet at least she knows she has this new bargaining chip that will give her leverage with her father, the fantasy she mentions to Tom of "grandpa bouncing his grandchild on his knee", but he dies right before making that a reality.

It explains Logan's divorce lawyer advice to Tom as well -- Logan did not want them to split. He wanted them to stay together, and have his grandchild, and keep Tom around as his pain sponge. The irony is that Matsson has carved out his own "Loganesqe" corner of this world and will now keep the abusive cycle between Shiv and Tom alive in this next chapter without Logan around. It adds context to Kendall's feelings of intensely disappointing his father, and his own conflicted feelings about not genuinely feeling a love and connection for his kids, but trying to pretend he does. It all goes back to Logan's existential dread at not securing a proper Succession of his lineage. In the end, I think he gives up on it in a way at the beginning of S4 -- and that is when he waxes poetic to Colin about life and death, and pivots to his "rebuild ATN like pirates" mindset. If his idiot kids can't protect his legacy, he'll go down with ship himself.

This is the full context we needed to understand this warped sibling dynamic living in the shadow of their father. Logan would make jokes about Kendall's kids "not being serious grandchildren" when he wasn't around. Shiv knows this well and even tries to stop Roman from going there because it hits a nerve. In the end, Shiv can't give her brother the win, whether to spite him or protect her own future, we can't say for sure. But what is apparent is that she falls in line to accept her place in the world her father would have preferred for her - carrying his grandchild and empowering Tom to keep the good family name alive. Kendall knows this, Roman knows this, they all know this. The air has been cleared.

Roman is free, Shiv is anything but free (by her own choosing), and Kendall is stuck being followed around by his father's best friend, paying him to hover over his shoulder as a testament that Logan was in fact capable of genuine connections, just not with him. A constant reminder of his past sins and his father's disappointment - a hired grim reaper of grief and shame.