On your first point, the main part reason the the Military and Oligarchs would take over was because of the war with Ukraine. NOT because they support it and want to alter strategy, rather because they are against the massive drain on both the standing Russian Military and Russian Economy. Further, a coup/assassination in Russia followed by increased attacks in Ukraine increases the global thermo Nuclear option. Both of those are terrible for the Russian Oligarchs and Military leadership. So, no, I think a coup/assassination greatly reduces option 1 and 4 in my post above.
As for US Tech Bro Oligarchs, it's less the actual tech itself that concerns me more the consolidation of power by having control and ownership of that tech in ADDITION to the tech control they already possess. I'm not in the camp of concern over Terminator power, while acknowledging the risk. Instead, I'm far more concerned about Terminator LIKE technology and power controlled by a small group of human Oligarchs, US or otherwise. I'm far more concerned about the situation prior to robots taking control. Hell, I might be pulling for the robots at that point.