The real problem of the Russian-Germans in the USSR after 1955 was not lack of territorial autonomy. But, rather the complete prohibition on legal assimilation in the Soviet system which led to a situation of acculturation into Russian societywithout acceptance into it. They were going to lose their German culture in the USSR no matter what in my opinion. But, the discrimination on the basis of being descended of German immigrants could be solved by losing their German legal catagorization. Allowing the catagorizing of acculturated Germans as Russians would have probably led to psychological assimilation as well. The immutable nature of being classed as Germans served as an artificial marker. It left them in a position similar to Blacks in this country during earlier times. No matter how much they adopted Sovietways they could not attain equality with other citizens.
The autonomy movement leaders in the mid-1960s were mostly Party members and they endorsed the nationality structure established in the USSR. They wanted a return to the policies of the USSR during the mid-1920s at the height of korenizatsiia(nativization). But, the violence of the dispersal and cultural repression during WWII pretty much shattered the German communities. They were much more fragile than other deported groups such as the Chechens or Crimean Tatars due to being a much less cohesive group and having far more recent roots in Eurasia. Restoring and maintaining a living German culture was a longshot even with restored autonomy. Even the deported nationalities that returned to restored autonomous territories lost alot of their former culture as a result of the exile. Most notably they found it very difficult to maintain their native languages against the assimilationist pressures to adopt Russian. The primary language of the Chechens and Kalmyks is today Russian.
Achieving legal and social equality could have been done for the Russian-Germans by one of three ways in my view. The first was within the Soviet system. That is to restore the Volga German ASSR and national raions to protect the Germans living in these territories from discrimination. This was the solution of the 1960s activists. It had problems already in the 20s and 30s. Not the least is that most Russian-Germans did not live in the Volga republic. The second was what the activists of the 1970s advocated and what became the accepted solution in the 1990s. That is mass migration out of Eurasia to Germany. This also has problems in that having lost their German culture they are considered Russians in Germany and face a new wave of discrimination. One that acculturation in a few generations, however, will hopefully end. What was never considered by Russian-German activists was a true civil rights revolution. That is the removal of official mandatory nationality classifications. At the very least going back to the pre-1938 practice of allowing free choice of nationality rather than making it hereditary. Even allowing an entry of Soviet might have helped some. But, nobody in the USSR could think outside of essentialist and primordial catagories of nationality that allowed for no change over generations. This put stigmatized nationalities in the same kind of bind as visible minorities in the west. They were always going to be marked as such.