I would say it's about time for something new, more fitting in the Arma verse, something most games never do. As in real life seeing a pivot to the Pacific, the most common run in, would be the PRC, or more commonly known... People's Republic Of China. Now of course, China is seen negatively IRL for some things it's don't, others not so much, but this is the Armaverse.
While the China is a friend IRL, it's also a good adversary in any video game. As per sick and tired of Guerrilla forces, i think a far more modernized armed forces such as that of the PRC, would be a much better competitor. And as being one of the biggest players in the CSAT, most likely a founder, i find it even more fitting they make a big appearance.
Now of course, that's just my humble opinion. Russians are cool too. I just think they're over done, ever since... The end of WWII.