I dunno, at a personal level, things we can wield, and touch, and manipulate, I think tech wise we're reaching a plateau.
The amount of energy we can personally marshal (and, at it's core, that's what personal combat is all about), whether as air pressure, chemical expansion, electrical discharge, I honestly don't see any orders of magnitude change in the near to mid-future. I think as a society, we have the fundamentals of the physical universe pretty well figured out.
Granted, I don't know anything. In many ways I'm as ignorant of the future as anyone before the wheel was invented. But based on our progression in physics and thus chemistry, material science, etc. I think we're about tapped out as to how much energy a person can carry and deploy (especially safely).
I mean, consider something like the RPG-7 and the Javelin. The Javelin is almost twice as big (from a warhead point of view) as the RPG-7. This part of what makes it more powerful. It's simply twice as big. But this limits the carry capacity for the soldier. That limit in the warhead size is advanced chemistry. I don't know how much research there is in more powerful, yet as stable explosives than what's in systems like the RPG and Javelin. But I'm betting whatever research is being done, doesn't offer an order of magnitude advancement. For many use cases what we have is "powerful enough" to where they can specialize in other ways (notably for the Javelin, in the electronics).
Look at the new XM5 rifle for the US. It's a larger, heavier cartridge, with a case that can withstand enormous pressures, but for twice the weight of the M4 5.56 cartridge, it offers 40% more energy down range. A key design of the new case is handling the higher pressures. A steel base mated to a brass body. The steel base is better designed to withstand the high pressure of the primer area (which it normally not very well supported by the action like the rest of the cartridge) to keep the higher pressures from blowing out the cartridge.
But, it comes at a cost of payload. Soldiers can carry half as many rounds now. And it should be powerful enough to defeat near term personal armor advancements, notably in composites and ceramics, as that was a primary goal for the cartridge.
We have more powerful explosives and propellants. We have better armors. But not necessarily that are usable by men. We're still limited to total payload and usefulness.
Things like the Gauss rifle use extraordinary amounts of energy. Orders of magnitudes in terms of battery density, wire stability (can you imagine the wires necessary to conduct the electromagnetic energy necessary to discharge a gauss rifle?), etc. Room temperature super conductors, perhaps, to the rescue here.
We already have problems with batteries spontaneously catching fire as it is now, they have so much energy.
Most of our tech development since Rome has been stumbling allong figuring out the fundamentals. Today, we seem to have a pretty solid understanding of at least the high level fundamentals that manifest for aptly in our physical world, at least at human scales.
The new XM5 is in no way fundamentally different from the same cartridges we were using 100 years ago. The new casing development is novel, but it's a blip on the power curve, not an order of magnitude we need to transcend this path of empowering people with power to kill each other, nor is it enough to stop being killed. Other than the case, the XM5 is just another predictable cartridge, another point on the same power curve we've been using since smokeless powder in steel tubes was perfected.
Advances to come, to be sure, but I think were plateauing the power were able to comfortably, and safely bring to bear at a personal level as human beings.
