Housing will not magically fall off a cliff all at once, it will be more like a wave that travels inwards from peripheral regions.
Heavily overbuilt exurbs are first to feel the hurt. It’s already very bad in Hemet. Temecula and Murrieta are getting there. When Temecula gets to $100/sq ft, people will start thinking “hmm why should I pay $300/sq ft in Escondido or San Marcos when I can have 2x bigger house for less money in Riverside County?”, Temecula will start stabilizing, Escondido and San Marcos will start experiencing slow sales and falling prices, etc.