I think that's unlikely, Yellowstone is monitored and I think it's more likely that US programs to prevent population decline/demographic collapse would work than Chinese programs of the same nature. I think it's reasonably probable that China will level out under a billion real population (not including migrant workers), even if you think the current official figures are real. Russia has massive HIV rates and is shipping a not insignificant portion of it's reproduction age males to Ukraine, and that's not good for it population in general, and may be catastrophic for it's more rural populations.