I always find it interesting to see people looking to kill J-10 upgrades.
They were still introducing new variants of J-7 and J-8 even after J-10 was inducted into service. By 2018, J-10 would've only been in service for 14 years. It will continue to be produced for at least 10 more years, probably 20 years imo. Simply put, J-XX has not shot of replacing all of the J-7/8 regiments that will be retiring in the next 20 years. So, you are left with two options:
1) keep putting in the same variant of J-10 we have been seeing since 2004
2) keep developing newer and better variants that will be useful well into the next decade and the decade after that.
Not only that, PLAAF will have to buy something that is much cheaper + less capable than J-10 to be able to replace all of J-7 variants that are retiring. It could either be JF-17, L-15 or some other design.
Now, if the fanboys out there think that China no longer needs J-10 upgrades and can just go straight to J-XX, why don't you tell me what kind of air force China will have and how they will produce them (remember to factor in cost and production capabilities).