If they ever come up with a twin engined version in the Typhoon weight class, its safe to presume they would stop building the single engined type. Whatever low end would be left to the FC-1, probably even imported from Pakistan. The resources to build such planes would be finite even for Chengdu, and I would probably put it on which plane it would be most effective.
I don't know if the so called stealthy plane and the twin engined plane are one and the same, but in my opinion, most likely are, as it is not efficient to be developing two planes at once. And it probably isn't as stealthy if it decides to recycle as much of the current J-10's front end.
Logically its simpler for the single engined J-10 to follow an upgrade path for the engine, to more powerful versions of the WS-10A or AL-31F. If they are pushing for a twin engined variant, two things must apply.
1. China intends to fully keep the plane domestic, ruling out future versions of the AL-31F or AL-41.
2. China's engine technology still has its limits. It would be easier to achieve the same thrust level with two smaller engines of less thrust combined than one single powerful engine with one overwhelming thrust. Note this lesson applied to the J-8II vs. J-9 development.
3. Chengdu intends to create a larger plane with a bigger wing planform that can hold more hardpoints and weight. Probably means much of the plane from the front end downward may be new, and probably longer.
IMO, if they are trying to retain the J-10 front end, DSI may be ruled out. Personally I was hoping of a plane with a front end more similar to the FC-1, but bigger, with canted sides and DSI, then with the canards behind the intake, followed by the main delta wing and twin canted tail.