Let us assume (it's called a working hypothesis), that all three parties, i.e. China, Russia & USA have equivalent stealth planes. in other words for stealth, F-35=Pak FA=J-xx (let's not include the F22 in case gambit has a heart attack here).
And let's assume there is a crisis and all 3 planes are thrown into the same airspace. HOW WILL ONE FIND THE OTHER??? It will be like blind, deaf and mute people fighting trying to hit one another with sticks.
So if you happen to see the other guy first, it might be good if you can also outmaneuver the other guy using canards or whatever else.
Plasma is too much of an exotic technology.
The russians have solved the problem and are years ahead of anyone else, but even they haven't solved the most major problem of them all.
how do you keep the plasma field around the aircraft at high speeds?
That is the major problem, not the actual tech.
The field can be generated, but any aircraft with any plasma output, will eventually reach a speed (changes with altitude) where the airflow will blow away the field faster than it can be generated.. hence..plasma is not realistic for now...