2) massive intersteller war ala succession wars all over agasin that would have left every state shattered and balkanized into 15 some odd successor states not 6.
Aleksander Kerensky leaving with the SLDF was a moral failure because he gutted the Terran Hegemony's army, left worlds unable to defend themselves who were not interested in assimilating into other cultures. This defiance is seen all the way into the Jihad. if you read those books you find many worlds in the Word of Blake Protectorate retained their sense of history, and knew that the houses claim to their world and interposing their culture was always bupkiss. they joined the Word willingly cause they were different, or at least promised a difference.
massive interstellar war could have still happened had a Blake/Kerensky combo been successful I don't think the League would have survived the change.
Kerensky leaving - I totally disagree. The Terran Hegemony for all its vaunted strengths was battered and almost beaten by the Liberation campaign - looking over Liberation of Terra points to dozens of worlds that were dead already. Worlds and units were already being courted by the Succession States AND the Casper net was a total and utter mess - because Amaris used it. They could not have stood up to all 5 Realms at once.
If Kerensky had stayed the First Succession War would have been even nastier in my opinion, the House Lords would have fallen on the Hegemony and Terra at its centre would have no option to opt out and remain neutral. None of the worlds would have been spared.
Because of the defiance these worlds still felt during the Jihad I think you would have had a hundred more New Dallas if the SLDF has stayed - every single world would be telling the Inner Sphere to screw themselves because the SLDF Army and Navy were on their way even if they were tied up at another brush fire.
Kerensky leaving did gut these worlds but it also made sure they were not all turned into charred rubble by the incoming Succession Worlds, most of them knew - we can't stand up to this, we surrender - only the really stubborn ones died. Kerensky leaving was a Tactical Retreat for the longer Strategic Game if Kerensky had found a safe haven he could have comeback. Unfortunately the Exodus didn't work as he planned