Complex sentence: Slovenia and Croatia will be independent, Serbia and Montenegro will be in the core of the new state and BiH and Makedonia will be in between, but BiH will be much closer to Serbia than to Croatia.
Split into simpler sentences: Slovenia and Croatia will be independent, Serbia and Montenegro will be in the core of the new state, and BiH and Makedonia will be in between. But BiH will be much closer to Serbia than to Croatia.