Will we ever find another planet we can colonize with some of Earth's population?

We may find an Earth-like planet someday, but unless we decide to terraform Mars next door, it will be impossible to accommodate many humans.

First it would be impossible to get them all there. The only way we will colonize space is to set up outposts of a few thousand colonists, make the outpost self-sustaining, and then let the colony expand its population from within. I am afraid we Earthlings are never going to leave the Earth in large numbers. Moving billions of people through space would be astronomically expensive. Growing them from colonists already there, however, is inexpensive.