What future space combat would really look like
Space combat seems pointless to me.What exactly would they be fighting over?Presumably you want to reach space for resources, so asteroids, planets and moons with minerals, stuff like that.  You might also want planets/asteroids/moons that are 'good' for colonization (easily terra formed or already life sustaining).You probably wouldn't see many fights where you are firing at the resource itself. No one with the money to fire at earth, will actually fire at earth, because it is more valuable as an inhabitable planet. If each side can obliterate whatever is being fought over, you basically have an instant MAD scenario.Similar with moons/asteroids. I'm not going to fire a massive kinetic weapon at a moon or asteroid (and blow it to pieces) if my objective is obtain that object to profit from it. More likely I'll pay people very well to infiltrate and sabotage it, repeatedly. I wouldn't even bother trying to invade.Why not an invasion force?
Well, you could send an invasion force, but that would be fairly pointless. It is easy to defend an entrenched position that your enemy does not want to shoot at (sabotaging just the defenses might be too obvious, and i think would have too high a possibility of failure). On top of this they can use massive force to repel you, and you cannot (you don't want to obliterate your objective). So an invasion fleet is probably not likely.A far more likely scenario would be to simply drive your competitor out of business. If they keep getting sabotaged, it becomes unprofitable for them to operate (it becomes a 'cursed' outpost, wages go up, you have to make repairs). Then you can easily take their stuff (or buy it on the cheap when they are going out of business).This gets you into interesting things, you would end up with extensive background and history checks, genetic tests to prove that you really are who you say you are, mental/psychological screening, mind-reading, brainwashing, complex hacking of the computers that do background checks, genetic 'doping' to make  a person pass as someone else, brainwashing.Your competitors will also likely try to assassinate you if they every figure out that you are the one ordering the destruction of their outposts (it should be easy to figure out, as there will be few entities with resources to profit from this).