I would argue that we do not need nationalism right now. Why? Because we’ve gone beyond it as we destroy our planet’s climate. If we don’t unite as a planetary society trying to save it’s civilization and it’s species, then we’re doomed and it doesn’t matter a fig where we live on this planet.
Extreme nationalism completely defeats our ability to work together on this issue. We can love our cultures, our language and our way of life of course, but we’ve got to change our political and economic planetary environment so that we work together for our children and grandchildren.
I can assure you the future is not pretty, and all that will matter will be food, water and guns and noone will care what country they come from!