0 chance it can spread. PAYGO systems in general were set up when expanding demographics were not in question. Nobody is stupid enough now to switch to a system

0 chance it can spread. PAYGO systems in general were set up when expanding demographics were not in question. Nobody is stupid enough now to switch to a system that requires an ever growing labor pool in perpetuity. The problem is that there is no "democratic" way to get rid of them because in most WEU countries retirees/close to retired already make up enough of the population to block any such measure at the ballot box. See for example France.