The video: https://youtu.be/xerdC6hN7x8
I don't believe sending troops up into space, but other members of the military, such as mechanics and engineers, research teams, and those manning the stations themselves. I think that most of the service members will be on the ground for the next 10-20 years. I wouldn't be surprised if by that time A.I and robotics were good enough to independently man the stations with humans ao-board.
It could be possible that we would need to deploy troops in space by say, 2100-2150 to better secure stations and possibly bases.
It is possible and very likely that in the near future we could begin mining minerals from asteroids and the moon. This may require an armed security force to protect it if space travel becomes advanced enough, which it may if you look at how fast Humanity has developed new technology.
(wow, I write to much)