If resources are limited and human brains can live forever in an artificial substrate, I see three possible futures: 1) Send of these brains to other planets.

If resources are limited and human brains can live forever in an artificial substrate, I see three possible futures: 1) Send of these brains to other planets. 2) Time-sharing bodies. 3) Destruction of old brains. I would not be surprised if the last option will be considered the most inhumane.