That's what I think.
Assuming you bought your flat for $500K but now market prices
for similar units drop lower to $400K.
Your life is still the same. Nothing has changed much, you still
pay the same monthly mortgage plus interests regardless of whether
flat prices have risen to $800K or dropped to $300K.
Except maybe you LL a bit because now people are paying less for
a similar unit because they bought at $400K. 
If I bought at $500k and the same unit drops to $300k, it will
depend how much equity I have in it. 
If I paid $100k and still have $400k to pay the bank, I might as
well rescind the loan, let the bank take possession of my HDB and
get a new one for $300k. 