Rosenburg was still a Nazi tool and assumed Slavic people are stupid sub-humans who wouldnt see through such a crude ploy. It's a moot point through, as the fundamental nature of the Nazi regime from top to bottem would stipulate against giving ''sub-humans'' even the pretence of being treated as anything but helots. Unless you replace the Nazi regime as a whole you'll see mass partisan uprisings, but in that case without Nazi's, WW2 as a whole would be void too...Of course this was undeniably true for most of the war, however, the initial reaction of many Soviet peoples and how many of them continued to support the German advances even after the Nazis showed their true colors leaves a whole host of implications to what -could- have happened had a less radical German regime used a strategy like what Rosenburg wanted.
The only ‘’non-Great Russian’s occupied were Byelorussians who are just basically Russians, and whose national intently even today is rather tenuous and almost non-existent in 1941, As for the Ukrainians, well aside from the former Hapsburg provinces in the west they were deeply sceptical about any hint of secession. Even after Stalin had starved millions of them to death. Tens of thousands quickly undertook partisan warfare in the forests eating acorns & pine needles. Again that is not the profile of a population ready to revolt or turn against the state. You whole thesis is flawed on that basis.If you replace the Soviet people with the Russian people you would be absolutely correct. However, not every nation in the USSR loved the Soviet Union nor the Russian Rodina, though they might have hated the Nazis enough to fight for it
Still even if what you said were ture, non-Nazi German invaders would still face major problems. As most, say Ukrainians could remember the last German-installed government from 1918, and would not have fond memories. It's one thing to gain ''independence'' or ''freedom from Stalinism'', and another to have it installed by an invader at gunpoint. Especially this particular invader.
Somthing like 40% of all Soviet troops were non-Russian so, after the clusterfuck of 1941. Had the Soviet populous EVER had even a substantial minority intent on overthrowing/turning against/or simply not serving the state it would have happened. ALL governments rule at the will of their populations. Soldiers and paramilitaries come from the population. If the soldiers won't shoot, the regime falls (something the Tsar learned to his sorrow).