This is a good question. If we agree to do away with national borders and the idea of competing national interests then perhaps we would also agree to do away with inter-nation sport. We might even see it as necessary to building global society.
But it appears that lots of people enjoy supporting their national team. Many benefit from finding a sense of identity or meaning in their allegiance. And generating a sense of common purpose can support helpful communal activity in other areas of life. So banning international sport could turn out to be objectional, oppressive, and directly harmful to society.
I can enjoy watching a football team from the village I live in beating the team from the next village just as much as I enjoy watching the team from the country I was born in play against a bordering country. Passports, borders, armies and ideas about national identity are not essential to sporting experiences.
We should try to preserve everything positive about international sport and make it better.
In a society for everyone everywhere, what could the first Olympics and Paralympics be like? The goal of identifying the best performer in each sport and category wouldn’t change and we could still represent, and support, places we are affiliated with. But the idea that nationality is linked to performance ought to be looked at more critically than ever.
For the first time we would have the opportunity to level the playing field (not literally) for people born in places where they have less chance to succeed in planetary sport, and to give people from those places the chance to cheer for someone from their neighbourhood.