I strongly suspect they will eventually be a single political jurisdiction. But that's not really the most important question, as I see it. What really matters isn't countries, but conditions on the ground.
In a sense, I don't particularly care where the government that claims me as a citizen is located, or what territory it controls. What I care about are things like how much freedom I have, how high the taxes are, whether my personal liberty and privacy are respected, whether I have the ability to travel, etc. If more people focused on those types of things, i.e. viewing the world in terms of peoples' quality of life instead of in terms of countries and national boundaries and so on, I think there would be fewer wars.
To use a sporting analogy, do you go to a game in order to root for "your team" to win over the opposing team, or do you go in order to enjoy watching talented people engaged in a competition? Of course it may be more "fun" to attend a game when you really care about the outcome (i.e. wanting "your" team to win), but imagine if people were getting injured and killed in the stadium as fans fought with each other, and players were being exploited by power-hungry coaches driven to win, etc. Then would it still be fun?
That's what the world is like. People identifying with the countries they live in (nationalism) causes them to support discrimination or violence against people in other countries, because they think that this will make "their team" safer, or more powerful, or whatever. Power-hungry politicians exploit these feelings to expand their control and make themselves richer and more powerful at the expense of people in "their" countries or others. Nationalism is as harmful and ugly as racism, sexism, or homophobia.