It is of course true that the J-20 is the best of the best currently in service, never to be exported (or at least not before the sixth generation fighters enter service in large numbers) but the J-35 is no junk at all, it is a very formidable asset that exporting it that early is very unexpected. For example I don't see how the J-35 can't go toe to toe with the F-35 over mainland airspace, integrated with ground based AD. I will be interested to see if any will be exported with the WS-19, because each one that would be exported would deprive the PLA of fielding a native variant.
If we're talking about the situation in 3 year's time when the first Chinese J-35s are exported, I frankly don't expect any American F-35s to ever reach mainland China.
The predominant situation would be (700?) J-20s conducting long-range offensive air missions against all the opposing airbases in the 1st Island China.
