The govt's new policy sounds more like a immediate stop to property investors, be it HDB or private. But not long term solution.
Previously the decreased max loan from 90% to 80%. The rentals started creeping up and then buyers started accepting and going for property with 80% loan. They buy smaller houses than what they could have got with a 90% loan but they still bought and pushed up the prices.
The HDB change is to deter investors from using HDB as property investment. This will help to some extent but real investors wont pay high COV for HDB, its genuine buyers for own stay which pays high COV. There will be lesser HDB sellers which will again push up prices after some time.
I see the next property boom to be bigger than the current one.