Although a few billion years is quiet a lot of time, the problem to be solved is also quiet complex. Finding an alternative planet is not going to be easy. Just moving from one city to another requires so much planning.... if we want to shift to a differnt planet... thats going to require much more planning. Some of the problems we are going to face are:
- Means of transport for such a large number of organisms and stuff.
- reconstruction of our planet on the new planet
- taking snapshots of earth...and stuff for the purpose of keeping track of our history