One element that held Bosnia together was the mixed population. But with the low number of Serbs in the Federation and the sense of discrimination among Serbs there an important element that held Bosnia together is falling away. If the international community wants to preserve Bosnia as a whole it should pay top attention to this situation. When the Serbs of the RS stop feeling connected with the territory of the Federation I see no future for Bosnia as a whole.
Postscript: the number of Serb returnees to the Federation is disputed. See this article.