Agreed. I do believe, however, that such a vast expansion of floor space suggests that the J-35/A will be procured in quantities comparable to the J-20/A/S.
From a fleet perspective, I think J-35 numbers and procurement should be significantly lower than for the J-20.
1. The J-20/A/S production rate is already at 100+ per year, whilst the J-35A is still only ramping up. At this point, it should be much easier to further increase J-20 production than J-35 production.
2. Chinese doctrine has shifted to long-range air superiority, which favours the larger J-20 over J-35. And there shouldn't be much of a cost premium for the J-20, if any.
3. US 5th gen fighter production is at 150 per year. You would expect China to at least match this, given the China-US arms race. That would mean J-35 production at a maximum of 50 per year, given that the J-20 is already at 100 per year.
4. But suppose they are aiming for 200 per year? Then I think the optimal ramp up and force composition would look like 120-150 J-20 per year, with the rest as the J-35. Yes, that should still leave spare floorspace at Shenyang, but I think there are other projects underway and future expansion.
5. And there is an outside possibility that Shenyang also starts J-20 production. Both Shenyang and Chengdu are owned by the central government, and the Director at Shenyang is a transplant from Chengdu.