tanks unlike drones can't go in a straight line up in the air, there's going to be a lot of backtracking and turning around. The fiber spools probably can't stand something like that.
I imagine things in the future will be daisy chained. Autonomous ground systems will connect to autonomous relay vehicles operating nearby wirelessly, who connect with other autonomous relay vehicles further behind (and can advance to fill gaps if frontline relay vehicles are inoperable), and so on and so forth until long range wireless or fiber optic communications are available.
Ideally the frontline vehicles should be able to do extremely time sensitive tasks entirely autonomously, like aiming, firing, and obstacle avoidance. Then commands fron the rear would just be for things like direction, formation, and target selection. This should maximize efficiency and minimize the effects of latency likely to be present in such a daisy chain.