There are no blue helmets there--it's a NATO mission. The Albs like the USA & NATO, but have grown to despise UNMIK, so a "blue helmet" force would be problematical. Similarly, the Serb memory of UN forces (remember Srebrenica?) is not exactly one that inspires respect. The USA & NATO will keep at least some forces there until negotiations are complete and Condi & the Prez are convinced there will be stability. It is likely, however, that the follow on to UNMIK & KFOR will be the EU, similar to what is going on in Bosnia now.
If the US pulled out, Serbs in Kosovo would move out from their barricades and begin fighting back with the same force the Albanians use. The Albanians would try and attack the remaining Serbs, a big mistake on their part.
Keep the US at Bondsteel, the presence needs to remain.