It's more a Chinese problem than an American problem, because the F/A-XX project is already in progress. China is trying to catch up to the United States, and if the projected J-20 is deployed right now, it'll likely be superior to the F-35, just as the F-35, if its program had been on schedule, would be superior to the J-20 in certain key aspects.
Basically, if a mature J-20 can be put out in numbers by 2022, it'll have five years of numerical dominance over the F-22 and qualitative dominance over the F-35. Towards 2028-2032, American sixth gens will hit the field, which will render the J-20 obsolete until the Chinese can catch up with their own sixth-generation kit.
But here's the problem; what happened to the F-35 was that its development was excessively prolonged, to the point where it had few advantages over its competitors, because while it was state-of-the-art during the design phase most of its technologies got cloned or hacked during its prolonged development. If the J-20 is similarly late with its "reach" technologies like its EODAS and proper 5th gen engines, 5 years of dominance could become 4, 3, 2, or 0.
As a good, loyal American this is not a problem for you. You must be interested in the J-20 simply because you like planes, and if its later technologies are 5 or 10 years late, no problem, it's still a beautiful plane. For the Chinese, however, this is geopolitically important because it determines how much military leverage they'll have in the region and the world between now and 2030, and if the J-20's add-on programs are late, it'll imply that sixth-generation fighters will also be late.
Basically, America is usually ahead of everyone else in planes; the US's cutting edge is a half or full generation ahead of everyone else's. This time, because of Lockheed screwing the pooch, America will hit parity with China for a brief interval, until it pulls ahead again with sixth gens. The question is whether or not China will also screw the pooch, then; if they don't, they have a chance of being briefly ahead, if they do, they will be a half-generation behind the US again.