I actually hope they make a twin seater, but not as a bomb truck (there will be enough JH7s, Su30s, J16s and future stealth bomber for that role), but as a air combat UCAV controller.
A slightly modified HMD would allow a pilot to take direct command cover a air combat UCAV (something like the Sharp Sword for example) and pilot it as if he was in the cockpit. The flight controls and head tracking equipment would all be installed as standard anyways, a physical switch/button and toggle between aircraft and UCAV control for the back seat.
All that means that there would only need to be minimal modifications made to the actual J20, and the back seat pilot could easily and seamlessly transition back to a much more traditional backseater role in the event his UCAV is shot down, runs out of fuel/ordinance (would have it autopilot back to a base, or handover control to a group station for it's RTB phase) or switch between the roles as needed.
The stealthy J20 could get close enough to the action where communication lag is a non-issue with minimal detection risk. It will also pack enough punch to be happily jump in to mop up after the UCAV dies or need to RTB.
I really think the first air to air UCAV will be backseat controlled from a nearby manned fighter, and the J20 is perfect for that role.