I think the most likely scenario is that the south breaks off because it's in their interest to do so. And the Euro becomes a northern eruopean currency bloc because that's where the comparative advantages of each area are aligned.
The least likely scenario, because Germany will never fold on this issue, is to consolidate all of the debts of the Euro-zone into the EU itself and have the ECB be the only issuer of euro-denominated debt.
The time to do this was about 25 years ago.
Germany is already folding on immigration, but still wants to use the politics of it to hammer the Visegrads over the head with it. I don't think it will work... because the major ones retained their own currencies.
And, from my perspective, you have scenario D backwards. Russia wants nothing more than an end of the use of monetary and foreign policy to subvert its re-emergence as an economic engine. Russia's issues are with the power structures in both the EU and the U.S., not with Europeans or individual countries.
The problem is the intensity with which both Americans and Europeans have been gaslighted on this issue many can't see this. And Germany is trying to play both sides to get cheap Russian gas to run its industries and control its flow back to states like Poland and grind them under its heel.
Germany's politicians, in my mind, are the freaking problem, and the German people are beginning to see it for what it is.
Great discussion, BTW. Enjoying this. :)
Certainly better Saturday morning than watching Netflix in chilly Chicago!