I have not read the thread, i'll just answer your OP. Someone might have said this already...
But in the future, things will probably be a LOT more automated with various droids doing all the menial work etc. Humans will essentially get to have a holiday for most of the time, perhaps just maintain the droids.
Human numbers will of course have to be kept in check if it is to be sustainable at all without planetary migration, i.e spreading to more planets in other solar systems.
If it is at all possible in the short term??? No, not without billions of dead people due to famine, disease, lack of transportation etc etc.