Not all communist ideology involves authoritarianism or statism.
What do you mean communism doesn't work when fascists are in control? (I would say that communism is by definition stateless but will not get so pedantic because I think you're talking about transition states.)
What socialist state that has been lead by fascists are referencing when you say that?
They are opposing ideologies, what do you mean when using fascist in this context?
They are "opposing" ideologies that hate each other, but their behavior in power seems a lot alike. Kinda like Christians and Muslims that way -- they both try to use legal criminal methods to enforce how they think people should behave and what people should do and both are capable of producing fanatics.
What I see happening in the two "Communist" countries that seem likely to remain so for awhile (China and Vietnam) is the evolution of an elite who run the country, no selected as in the past from ideological purity and corruption and nepotism, but selected from among those who finish college and/or military duty successfully or with honors. Some ideological "purity" will probably be needed, but more along Leninist lines, not Marxist and certainly not Stalinist or Maoist. In short most of the party members will be a genuine elite. This will avoid the problems of politics and the corruption and money and stupid voters who ruin Western democracy. The danger of course is that party members will always want to somehow get their children also in, and this will be an ongoing issue.
Then, again, the Party stays legitimate in most local eyes now because it has produced prosperity, but this has largely been sheer luck, as the party leadership is arbitrary and changes policy too often and too stupidly. However, the world has been doing well (in spite of all the complaints) and so they have been able to ride the rising tide. They need more professional, less political and certainly less corrupt people in power. They no longer have any legitimacy out of ideology (the rising of the proletariat and all that), so they need a better source of legitimacy than one that could vanish in any world turn down. I think the idea of a fairly selected, competent elite might work, if they actually do it.