Imma try coming at this from assuming this is a real possible future. They have to figure out the energy density problem. Currently the capacitor tech we have now, is orders of magnitudes larger than the "rails" and projectiles, and because it's so high voltage the wild literally rips themselves apart, or if there's a slight problem, weld itself fucked. That is really the biggest technological hurdle we have currently. So if China gets super/mega capacitors, finding the chemistry wouldn't be too terrible hard. They already have the battery tech figured out with fusion cores, but it would take time to charge the capacitors so we're not going to be getting 100 + round per minute semi auto style firing.