The key word here is 'possible'. Regardless of whether or not it is discovered, given modern understanding of the relation between space and time (relatively), it is more than probable a method of transportation across dimension is available, given our resources.
Now whether or not humanity is -clever- enough to develop these concepts in the allotted time is up for debate. After all, instantaneous space maneuvering is already an observable phenomenon, but unfortunately, it requires an unprecedented amount of gravitational force (e.G. Mass) in a proportionally small volume in space.
So the theory of light-speed travel came to play. However, strangely enough, this theory seems even less probable than the theorized 'Wormhole'. And then there remains the issue of time relativity. Increasing velocity, approaching the same magnitude as light, will slow one's perception of "time" to closer to a standstill than in slower motion.
The closest star to us, besides our sun, is Alpha Centauri which is four light years away. Light travels just below 5.9 trillion miles a year, meaning the Alpha Centauri is 23.6 trillion miles away. It would take several hundred thousand years to get there by means of our current shuttles. That is just one star of 200+ billion in our galaxy, The Milky Way, which is between 100 to 120 thousand light years across. The nearest major galaxy to us, is Andromeda which is 2.3 million light years away. We haven't even put a person on Mars. Mars at is it's closest is 33.9 million miles away, and 250 million at it's furthest. The only way we will be able to travel across our galaxy, let alone to another galaxy is if they every find a way of making the Alcubierre Drive, or something similar possible. As for now, it will be hundreds if not thousands of year before that is possibly a reality.