Because of how cheap, refined and effective conventional firearms are, I have my doubts that we will ever see man portable alternatives. Lasers don't really confer much of an advantage at that size, and over the distances that infantry weapons are used at. Maybe as a sniper rifle alternative though because you don't have to account for wind or gravity, and stationary emplacement would let you set up a battery on a cable or something.

I think we're only going to see energy weapons in applications where they actually confer a substantial benefit over ballistic weapons. Like shooting down drones and missiles, detonating explosive vests or boats from a distance, that sort of thing. Railguns, similarly, make a lot of sense on battleships but not much sense on a man portable scale since a rifle will do the same thing for cheaper.