IRAS doesn’t need to do much; all they need to do, is to add 1 more layer of 5% for Buyer Stamp Duty BSD for amount above (says) $1.5M, a threshold for almost all HDB properties but decent sum for private properties.
Ie, no change on BSD for properties below $1.5M (says) but 1% more collections for amount above.
BTW, they had done the same in Feb 2018, without much fanfare.
