Kinetic projectile weapons will never be replaced by energy weapons on a personal basis. No level of laser power can kill with a single shot or even a number of them. the very best that can be done would be to use a full, long duration beam and saw the opponent's body open.
Projectile weapons are the best ,most effective short range weapon possible. One cartridge weighs very little. A rifle and even up to a thousand rounds can be easily transported by a man, maybe two. Can a laser or other energy weapon be made that can discharge a thousand lethal attacks in a matter of minutes?
I have one more point to make. An energy weapon would require an enormous store of energy, and it would have to be able to discharge it almost instantly when the fire control button is activated. It would have to recycle rapidly. It would have to be portable and lightweight. A rifle can pour fire out in seconds, can any sort of energy weapon put several hundred shots into an area of cover in seconds, hoping to make a hit?
Alright. Now if you have a sniper position, what does that change?
A super heavy backpack battery can be used, a battery that can accomodate the needs of a high power energy weapon. Put a super, absolutely accurate rangefinder on it. Out a super, ultra accurate telescopic sight on it. You will have a weapon better than almost anything we have now. Trajectory, wind drift, distance, none of the handicaps common to projectile weapons matter anymore, none of them. If a target can be seen and ranged, the hit can be made anywhere out to the end of the earth.
Punching a hole in the guy won't help much. But what if there is a short burst, a second or so? What if the beam drifts a bit during that second? Set the thing up to make an eight inch slash at the range that the target is estimated at. If you have the necessary power, you could open a guy's chest up clear to the spine.
But with todays technology, there is no such thing. You can't have the power to carry, or the power to dumpe enough energy in the short time available.
A pound of powder releases a ton of energy We may never find a way to store and channel enough electricity to make a hand carried energy weapon function.