Yeah, 30 is possible and not good at all for a lot of people, especially recent buyers, imagine saving up say a 20% deposit, putting down say 60K on a 300k property and then it drops 90k or so... Like fine if you're in your forever home but otherwise you're stuck of a bit then in negative equity and could take another while to even get back to break even/no equity.... and once you're back to break even you've basically got to save for a deposit all over again (albeit via capital repayment) if you want to move house to a similar property or upgrade.
I mean at least you're not renting and if you have a steady job then meh, no one is going to evict you but still, could be a lot of very angry people if it goes that far.
I guess people forced to sell + foreclosures at auction are going to have to take what they can, others are probably going to be a bit sticky with the prices they're willing to accept initially and will perhaps leave homes lingering on the market with no offers.