Kosovo (or most of it) will end up autonomous with a heavy UN presence, including a large Russian contingent. Milosevic (like Saddam Hussein) will not be toppled by war unless a full-scale invasion of Serbia from Hungary occurs. This is probably unacceptable to the Russians and, as in Iraq, the allies won't have the stomach for the chaos it would cause. Serbia will have to be rebuilt, perhaps with Western aid, to try to create stability if not liberal democracy. The other Balkan states will be in effect controlled by the continuing Western military presence.
The answers to other questions are less easily guessed at. What will this do to Russian domestic politics? How does Nato get out of the Balkans, if it ever does? Who if anyone will be brought to book in The Hague for the war crimes? What alliance will be forged to stop the US and its allies from going to war whenever it wishes?
It is only when there is a thorough public assessment of the effects of the Nato action that the servicemen and women in the front line will find out what they are really risking their lives for.