It's not really a problem for them. Today, they cannot fight the US anyway, but the sheer size of their air force is big enough to just move some around to fight us with.
All they have to do is bring 300 jets out of their total inventory of 1000+ 4th gen jets into the area and stop us from bombing their troops, ie only perform air defence. But we can't do that anyway since we have only 10 squadrons available instead of the usual 20+ that we need for conducting offensive missions, or the 30+ that we really need since war in the mountains isn't going to be short and we need attrition replacements during this time.
The J-20's potentially longer endurance than the Flanker can pose a challenge to the IAF. They already seem to have 2 regiments of J-20 operational while we do not have even 1 Rafale squadron available yet. And this is not even counting their whole host of long range SAMs in their inventory currently.