How will the military be organized in the future?

I mean when we have space travel (if we ever do). Will there be like a navy still? Cuse water can be just navigated by aerospace. Will we just have like a Air Force that can go in space and atmospheres of planets and maybe a Army for close quarters? I play video games all the time that reference space marines lol.
Sorry if this question is misplaced just kind of random today.

Right now the USAF is charged with defending space. I see if things go as they have in the past, we will have an independent Space Command, separate from the USAF like the USAF separated from the US ARMY after WW II. It is quite likely if we have "large" warships in space they will be run like Navy ships are today. For that reason I see the Space Command as wanting more small "fighter plane" type ships than bigger ships that would be more like Naval vessels.

In other words, the same stupid arguments between the branches today will carry into the future.