What about have the Weimar authorities execute Hitler for his role in the Beer Hall Putsch while the USSR goes all out Trotskyist?
The idea that Trotsky would be any more anxious than Stalin to precipitate a war with all of Europe (and America) seems more than dubious to me. As I wrote here recently:
"Furthermore, even if we assume that Trotsky was more anxious than Stalin to encourage revolutions abroad, that is not the same thing as invading foreign countries with the Red Army. On that, Trotsky seems to have been if anything a bit more cautious than Stalin. Trotsky seems to have been at first reluctant to cross the Curzon Line and invade ethnic Poland in 1920. (Some people have questioned this, but Richard Pipes, not exactly an admirer of Trotsky, has defended him on this point: "Several historians have questioned whether Trotsky really opposed the invasion of Poland as he later claimed...But the documents cited against him date from August 1920, when the matter had long since been decided, and Trotsky, having fallen in line like a good Bolshevik, naturally desired a quick and decisive victory."
Russia under the Bolshevik Regime, pp. 182-3.) In 1940 he was somewhat critical of Stalin's military expansion, remarking " Robespierre said that people do not like missionaries with bayonets. Naturally that does not exclude the right and duty to give military aid from without to peoples rebelling against oppression. For example in 1919 when the Entente strangled the Hungarian revolution, we naturally had the right to help Hungary by military measures. This aid would have been understood and justified by the laboring masses of the world. Unfortunately we were too weak ... At present the Kremlin is much stronger from a military point of view. However, it has lost the confidence of the masses both inside the country and abroad..."
https://www.marxists.org/archive/trotsky/1940/xx/ww2.htm (Admittedly, once in exile Trotsky had an incentive to criticize almost everything Stalin did, so this is not proof that he would use the Red Army abroad less than Stalin. But there is no good reason to think he would have used it more.)"
Furthermore, without Hitler's hatred of "Judeo-Bolshevism" and desire for
Lebensraum what motive would a non-Nazi Germany have for going to war with the USSR--which did not occupy any territory claimed by Germany and which actually helped Germany evade the military restrictions of Versailles? Indeed, Hitler faced dissent within his own party on his anti-Soviet obsession. Hitler actually acknowledged that his hatred of the Soviet Union was going against the grain of many on the German Right--even the völkisch Right--who wanted a German-Soviet alliance; he complained in
Mein Kampf that "today even folkish circles rave about an alliance with Russia..."
http://books.google.com/books?id=GcfYq-T3liUC&pg=PA38 Gregor Strasser was later to change his mind, but in 1926 he said "Our enemy in the East is Poland, not Russia onto which we do not border." "Even Alfred Rosenberg, whose views helped to determine Hitler's total opposition to a Russo-German alliance, regarded Poland as the main enemy and admitted the need for a temporary Russo-German alliance..."
http://books.google.com/books?id=X8T248Aer0kC&pg=PA64