Air superiority and interceptor in modern terms mean nearly the same thing. The only difference is that the latter is usually left to more high end fighters, since they need the extra performance to penetrate enemy defenses and hunt them on the enemy terms, rather than just neutral air superiority.
I think at the start when there was not that many J-20, they would be the designated interceptor aircraft. But today, there's enough to fill a wide variety of roles.
In 2025, J-20 would still be the go to if say radar finds evidence of F-22 formation over Kyushu, we have to fly there fast to fuck them up. But unlike in 2019, J-20 can not ONLY be spared for that purpose but can be spared for "easier" missions.
And in some years, J-20 will probably leave interception/deep penetration missions to J-36 and only fly alongside as backup if at all. Basically what J-16 does today.
