It is possible that the J-20 will be improved — including finally being worthy of the airframe — yet for now, the Mighty Dragon seems to be a mere facsimile of the Raptor.
The production facilities and supply chain for the F-22 were cannibalized for the F-35 Lockheed Martin cannibalized a great deal of the F-22's production infrastructure to support the ongoing production of the F-35, meaning it wouldn't be as simple as just re-opening the plants that had previously built Raptors.
The F-22 engines produce more thrust than any current fighter engine.
Even with this new fighter design, some question whether it can truly stack up to its predecessor.