@Xelda
But it's been open since the beginning of this story - however long that's been.
Wormholes, like the gate in this story, oftentimes are temporal anomalies - spatial 'security breaches' that get patched out over time.
Haven't watched much sci-fi, have you?
The story could end with the gate remaining open. The author is free to write this how they want.
Most stories involving gates to other worlds tend to go the way of said gates causing catastrophes if they aren't closed:
-worlds merging, in a rather destructive manner
-war, instigated by greed
-a hidden, malevolent 3rd force looking to conquer their galaxy, as well as the one open to them, thanks to the wormhole
-if the wormhole were to be successfully analyzed and replicated, and that technology is used for the wrong intentions...