I think kinetic weapons are still going to be big, and relativistic weapons will be the ultimate test of human morality and fitness to survive.
Hundred-ton tungsten slug at .75c. Very difficult or impossible to pinpoint its exact location (You see it 100 light years away, it's actually 25 light years away. By the time you calculate where it should actually be it's somewhere else). Probably impossible to destroy, redirect, or otherwise protect from, assuming no magic technology. Capable of permanently rendering a planet uninhabitable. And, most importantly, a necessary corollary of interstellar spaceflight (If you can send a ship at relativistic speed you can do the same with a slug).
If we meet another insterstellar civilization, they'll have the same technology. If they, for whatever reason, decide to launch a relativistic attack, we're fucked. If we decide to strike first, we just wiped out millions of years of evolution because we're scared of aliens. Can we trust a race we know literally nothing about, and what if that trust is misplaced? A lot of people say reaching that level will only be possible if we're culturally advanced enough to be friendly. Sure, I can see that, we can't keep wasting our technology on murdering each other, but who says that applies to other species?
Who says any of that applies to aliens? What about a hive situation where all individuals are in naturally perfect harmony without eliminating capacity for aggression against other species?
That's scary shit.
To answer the question: I'm not sure "space combat" is the best description. More, "space killing"