I would do the following:
Bring Turkey into the EU and put some troops on the border they have with ISIS.
Give the Kurds a country. They have been in charge of Northern Iraq for decades now anyway.
Use troops in Turkey and Kurdistan to shore up ISIS borders.
Wait for the Syrian civil war to end.
Hopefully ISIS's territory will then recede to nothing. Once they are a mere terrorist group we can contain them and negotiate with them until they disappear.