VI, day or two I read, that in order for Russia to conquer ISIS, it will need to put 350,000 ground troops in Syria. This is a huge number, which Russia cannot afford. Asad controls only 1/5 of the country and he will never recover his state. ISIS control 12 million people and if the population would not stand behind this regime, it will not be that successful. It is illusion to think that Sunni Iraq and Syria will "liberate" their territory from ISIS with the help of foreigner. It will not work. Population there is dreaming of ancient Caliphate that will return and restore glory of long lost past. Even if Russian/West coalition conquers Raqqa, the capital of ISIS, the ideology will not disappear. ISIS is not the only war of the Islamist ideology, there is Yemen, Mali, Nigeria, Libya, and West/Russia does not have money, will, resources, and leadership to control them. The best the world can do is containment.
What you propose is grand coalition, which would backfire in Russia (the largest Muslim population in Europe, Moscow itself has 2 million Muslims), and Western Europe which face a possibility of internal war with Islamic refugees. Americans thinks that they have superiority and putting a huge hope for Trump to be elected and sent tens of thousands Americans to fight in ME and defeat ISIS, but again, there is nothing to really conquer. How you will deal with Islamic ideology that has a huge support among 1.2 billion Muslims from Africa to ME to Asia? Capture of ISIS territory will not address it.