Su-30 MKI has both canards and TVC.
And the Russians then decided they could do without canards on the production Su35. There are no plans to put TVC on any of the Eurocanards...
Back on the subject of using the tails as air breaks, well I guess it would make some sense to do that, as the RCS hit will be smaller compared to deploying the full air break.
It could be that what the J20 designers are doing with putting that massive air break on the J20 prototype is similar to what the Russians and Americans did with putting canards and TVC on test planes - to see if actually both were needed or if the design requirements could be met with just one of the two.
I am sure that having both canards and TVC as well as having both an actual air break and being able to use the tails as air breaks all have their own separate advantages, and it would be better to have both as opposed to one or the other. However, all the different features also come with their associated costs, and overall, the platform could be better off if only one of the two is retained.
So the Russians decided they didn't actually need the canard on the Su35, and it could be that with tests, the Chinese decide the J20 doesn't need a dedicated air break when they can use the tails and replace the air break with a big assed fuel tank or more avionics on later prototypes or the production model. The world of design is as much about compromises as it is about inspiration.
