Electrothermal-Chemical guns work by using an electrically ignited plasma charge replacing or supplementing ordinary chemical propellants to achieve higher muzzle energies.
In game, this would be a gun-pod type weapon with higher velocity projectiles that uses energy to fire. These weapons cannot fire without power. The implications are obvious. Dogfighting at greater ranges with more powerful guns in exchange for using power that might be needed to run your jammer.
The realism should be fine, since much like railguns these weapons already exist as prototypes and seem to be a likely near future technology.