China has collapsed multiple times: in 1967, 1960, 1937, 1916, 1856, and so on. Another collapse probably isn't imminent but based on historical patterns it's entirely possible in our lifetimes. There could be an external shock in terms of a severe disruption in food or energy imports, or an internal power struggle between CCP factions. And even if China doesn't exactly collapse, a slow stagnation like what happened to Japan after 1992 is quite possible.