By the way, I don't think Trotsky comes out ahead in a world of female Stalin or no Stalin at all. One of the reasons Stalin rose as high as he did was that he was Not Trotsky. The Old Bolsheviks were by and large intellectuals with an obsession towards history, to them Trotsky was such an obvious Bonaparte that they felt he had to be stopped. Trotsky was also too much of an obvious heir to Lenin for the liking of a lot of folks near Lenin, who remembered when they were all neo-equals, smuggling newspapers in their underwear across the borders of European kingdoms. He was also a man who was very, very smart and knew just how smart he was and enjoyed showing people the level of his intelligence. Being the smartest kid in class even among Bolsheviks was not always a stellar thing. His personality was gloriously abrasive and he gloried in the dramatics, including how he dressed and dressed people in his posse (he had a custom uniform for men of his armored car unit - all leather and shaded scarlet, babe). He looked and acted too much like The Man of the Hour before his hour had come to become The Man of the Hour.
I can see Kamenev, Bukharin and Zinoviev forming a block to stop Trotsky. But I am not sure if they had the guts to truly stand up to him. They would have needed a goon in their midst to go and say and do the things that had to be done to stop Trotsky. Someone who knew that they could go into the hallway after a Trotsky speech and whisper, "Ya know he's a Christ-killing Jew, ain't he? Just saying, comrades. Just saying." And then walk off and let the Russian anti-Semitism whirlwind. Given there were no shortage of amoral killers in the Bolshevik ranks, I'd like to nominate Lander for this position, if push comes to shove, but he was a schismatic. So maybe Beria could have shown up and learned how to suck up to someone in charge and do their work. Yagoda was good for a shooting and character assassination, so long as you left him alone to enjoy pornography and sex toys afterwards.