Look at what's happening in the world right now and what the values of nationalism and individual nation-states inevitably leads to: 195 competing countries each with the ability to wipe out the human race. The human race can not survive in that world once current trends reach that level.
How do you propose to deal with that reality while maintaining the level of sovereignty that individual countries have in today's world?
I don't think the answer is necessarily globalism but some changes might have to be made if we want to preserve a world for our grandchildren.
I'd say that it's a pretty crude idea to think that the individual nation-states are "competing", and that they're a threat to the human race.
Do I feel like I'm "competing" with the Greeks or Swedes or the Irish? Nope. I don't give much of a shit about competing with them. I, along with probably 99,9% of other Finns, are probably too concerned with we are doing ourselves, to really give a crap about the rest of the countries.
It's only the few remaining imperialist (not nationalist) structures that are a threat to the world, due to their hopes of establishing a "world hegemony" under their own structure, China, Russia, United States, etc. (which are not nation-states but federations consisting of numerous states and peoples) along with the few remaining rogue states, left-overs from the WW2 era like North Korea.
The nation-state ideal is to have a common people, united under a common language, culture and history, working amongst each other, for each other, producing the best possible results. Once you bring in conflicting elements to the equation (for example hard-line Islam alongside Western secularism), that is when conflict is bred.
