Does the war have an ending in Planetside 2?

By design there is no end to the game. Factions can be pushed back to the warpgate but, no matter what, there will never be a victory. This won't ever change in the future either. It is one of the main points of the game and the one people have the hardest time to get used to.

A common question is: "If there is no 'victory', what is there to fight for?" and the answer to that is simply: "It's a sandbox. Set your own goal, find people to fight for the same goal and go for it. You decide whether you won or lost and even fighting losing battles can mean a victory for you personally."

The game has changed since the previous answers. Now continents can be conquered, in which case the entire continent becomes held by that faction for a while, including all the warp gates, and other factions cannot spawn on that continent until the continent resets. Any remaining troops from before the conquest are still on the map though and can fight while they last.

Esimir and Amerish get conquered by one team practically every day. Nothing special happens, besides the map screen displaying "last conquered by <team name>" in the corner. At that point, most players from the winning team just move to a different continent, since there is nothing left to capture.

Indar does not usually get conquered, because there are so many more players playing on it.

Note that the continents cannot ever be completely captured, since it is not possible to take over another team's warpgate.