I'm sorry, but they are going to face each others. There's already the rule according to which Cev doesn't allow more than 2 teams from the same country in the semifinals and more than 1 in the final. This rule has been created 15 years ago in order to avoid all-italian finals
I don't remember exactly when it was created and how often it has been changed/re-established over the years (including sub-rules concerning diversity of semifinalists and finalists), but it surely wasn't 15 years ago. In 2004, meaning 13 years ago, we had an all-Russian final in Belgorod between the hosts Lokomotiv and Iskra Odintsovo. CEV introduced that rule a bit later, I think, and I was too young to remember/know what it was like in the pre-Champions League era