If I had to guess, the property investment train just can't keep going on forever - eventually I'd imagine it has to top out as nobody can afford to live anywhere anymore. The younger generation is locked out of housing markets completely, and only through family inheritance is owning any property affordable unless you are lucky enough to be in a boom area at the right time.

I could just see any major region having a housing crisis cause the dominos to fall - if the Taipei market takes a 30% dive, all those investors need to park their money somewhere else, which will over-inflate other markets even quicker. That or some pillar holding up one of the markets failing (Ad economy stops returning fat multiples as saturation sinks in). It may be my perspective as a younger person but the economy has always been extremely fragile as long as I've been alive, and it seems like while investments have gone up over time the bar to getting in is higher than its been in a century.