Given that their rebellion never got beyond the 'strong words' phase, I doubt the minor nobles will be killed. The ringleaders and those serving them in the leadership will have to be made an example of but the majority of them will probably be given the option of The Wall or Exile from the Riverlands with their families intact.
A black mark to be sure but nothing a few generations can't clean up.
However...given that SI is Don Tully, I could help but remember a certain scene from somewhere before.
Vernon Roche offered a glass of wine to his guest.
The man accepted it steady hands. He swirled it around the cup before bringing it up to sniff.
"Things will be ok, Lord Quentyn. Do not worry about it."
In another time, Quentyn would struck the man across from him for his casual tone. Not now. All the fight, the rage, had left him. "Is my family safe?"
"Of course. Your brother, wife and children are safe."
Lord Quentyn took a small sip and frowned for a moment at the bitter taste. Across from him, Roche sipped at his own wine and he relaxed.
"When we let him go, he left for your lands straight away, veering neither to the right nor the left."
"Ha, my brother. He should have been the Head you know, always more capable...but for an accident of birth...If he was Head, he would have been a Minister. He would have been important. A member of the Cabinet. He wanted to throw in with the King against the Ironborn you know. Not me. I was afraid. Weak."
Quentyn lowered his head, sighing as he looked out over the beautiful estate he was ensconced in. Birdsong filled the air. The faint laughter of children and the annoyed voices of their guardians echoed in the distance.
It was a beautiful day and it made the wine he drank all the more bitter and sweet. "...Vernon...what do I do now?"
Vernon reached out and placed a hand around his guest's shoulders, leading him away from the children.
"You were always interested in politics and history, my good man. You know, the Ghiscari Empire of old..."
"And the Tully family, is it like the Ghiscari Empire?"
Other men might have taken offense at the impertinence but Vernon's face softened and he continued to move inside and his guest followed cup still in hand.
"In the old days, when a plot against the Emperor failed, the plotters were always given a chance to let their families keep their fortunes."
"True. But only for the powerful nobles. The petty nobles and their hedge knights were all killed and their estates were unto the Emperor."
Vernon spared him a glance.
"...unless of course, they went home and they killed themselves.... then their families were spared..." Quentyn gave his host a brittle smile. "Their families were provided for, isn't that right Vernon?"
"It was a good thing, Quentyn. Magnanimity and mercy."
"Yes. Yes it was."
Vernon clapped his hands a man brought forth an unopened bottle of wine. Quentyn paused for just a moment, afraid, before he broke the seal and poured. He stared, blinking at the deep red ripples. Breathing in the scent of berries.
"Do not worry about anything, Lord Quentyn. It will be alright. I promise you."
"Thank you, Vernon . Thank you."
Lord Quentyn raised the cup to his lips and drank deeply.