As I said, much depends on exactly when Stalin dies. The Sixth World Congress of the Comintern was held in the summer of 1928, in a transitional period, when signs of differences between Stalin and Bukharin were evident to the sophisticated, but officially harmony still prevailed and Bukharin was still nominal leader of the Comintern. After that, events developed rapidly: Bukharin's September 30 *Pravda* article, "Notes of an Economist" which was a cautious but unmistakable warning against Stalin's Left turn in economic policy (though disguised as an attack on Trotskyist "super-industrialists") and Stalin's attacks on the "Right Deviation" (by November he was naming associates of Bukharin's as the chief offenders, while still pretending the Politburo was united).
By late 1928 it was apparent that Bukharin's leadership of the Comintern was pretty nominal. In October 1928 the Comintern took the side of Thaelmann in the struggle for power in the KPD against Arthur Ewert (who was accused of "conciliationism" toward the German Rightists). In November 1928 the Comintern issued a letter to the American Communists, sharply critical of Jay Lovestone's leadership (Lovestone was a close friend of Bukharin). By December 1928 Molotov attended the meeting of the Comintern's Presidium and Bukharin did not. "After the Sixth World Congress, Molotov had moved into the Comintern as Stalin's deputy and Bukharin's de facto successor without fanfare or even announcement." Theodore Draper, *American Communism and Soviet Russia,* p. 388. Bukharin was supposedly ill. Bertram Wolfe, who had been sent to Moscow by Lovestone to strengthen Lovestone's position there, bumped into Bukharin in front of the Hotel Lux, where Comintern officials lived. Wolfe was surprised at Bukharin's healthy appearance, and asked him, "Well, are you well or ill?" Bukharin answered wryly, "By a vote of five to four, I am too ill to function as Chairman of the Communist International." Deaper, p. 393.
Now it is of course possible that the Rightists will make a comeback after Stalin's death. The downgrading of the leading Rightists had so far been unofficial (except for the removal of Uglanov from the leadership of the Moscow party organization) so the remaining oligarchs could pretend if they chose that it had never taken place, that the attacks on "Rightism" had not been aimed at Bukharin. (Bukharin's meeting with Kamenev, which did so much to damage Bukharin, could still be kept a secret, though pretty well known by rumor.) Some wavering Politburo members might switch to Bukharin's side after the difficulties of collectivization became apparent in 1929. But Bukharin would still face problems. He once described himself as "the worst organizer in Russia" and he was not wrong about that...Incidentally, he would probably *not* become General Secretary but something more like chief ideologist and "unofficial" leader of the party, like Deng Xiaoping in China decades later. Tomsky was believed to be the Rightists' choice for General Secretary (which would probably be a less powerful office than under Stalin) with Rykov of course continuing to serve as Premier.