I seriously doubt that.
Oh, the Bosnian Serbs might fight to join Serbia, because they don't want to live in a Muslim-dominated state. But Serbia isn't going to "send in its army to protect them", because Serbia is STILL paying for doing that during the Bosnian wars of the 1990's.
Maybe the Serbs will get a little help from the Russians. Do the Europeans want a fight with Russia over a little border changes? I think Not.
Fiction. Christians have always been the majority. Muslim 40%, Orthodox 31%, Roman Catholic 15%, other 14%