The Comintern disappeared decades ago, the Chinese revolution has been reversed, and the Vietnamese revolution was transformed into a nationalist movement that installed Vietnamese capitalism, not socialism. Once in power, Vietnamese nationalists invaded neighboring Cambodia. Marxists believed up to the 1960s that there was both the reactionary nationalism of oppresssors and the progressive nationalism of oppressed people. We decided almost three decades ago that the position of Marx, Lenin, Mao, and Ho on nationalism was no longer correct. I might be wrong, of course, but I see a lot of evidence today to support the view that all nationalism is deadly for the working class.
Capitalism exists throughout the world.
It has already existed too long, and it is not progressive anywhere for people to fight for more of it. The nationalism of victims of genocide, such as Jews, has become the racist ideology of Israeli Zionism that is used by U.S. and European imperialists to control the Middle East. Nationalism in the former Yugoslavia and Rwanda has recently been used to mobilize masses of people to engage in horrific genocide and ethnic cleansing. Black nationalism in the U.S. is used by the fascist Farrakhan to try to forge a not so secret alliance between the Nation of Islam and the hard right white fascists such as Lyndon LaRouche, the White Aryan Resistance, and the militias. If you think there is still progressive nationalism today, you should say so and analyze examples.