Let me address each of the "Can'ts" above.
1. For newly TOP residential properties, it's impossible to "Can't find tenant". It is just a matter of price. Even in bad times, by lowering the asking price to an attractive level, you will be able to pull tenants who are currently staying at older properties and perhaps paying the same or higher rental.
For commercial properties, it's possible to "Can't find tenant" if the location is bad and at some obscure corner of the building. However, for residential properties, there will always be tenants although some may not be desirable, such as the oldest profession in the world.
2. "Can't find buyer" is possible if the market turns bad, unless you are prepared to accept a loss.
3. "Can't service the loan" is quite unlikely given the current interest rates. My SIBOR loans are all around one-point something percent. The rentals are more than enough to pay the installments (principal + interest)! Which means every month my tenant is helping me pay off my properties.

Even if the rental drops further, there is still room.
4. Which brings us to the most important question "Interest rate go up" ... If the government squeezes this trigger, there will be blood, lots of blood ... not just the blood of property investors, but many innocent victims and bystanders.
Will the government squeeze the "interest rate" trigger before the economy recovers? I don't think so. I believe those people who queued up for condos also don't think so.
By the time the economy recovers and the government wants "Interest rate go up" ... property prices will be over the moon already.