This doesn't make any sense to me either.
If you're concerned (for some strange reason) that you will have "too much" CPF LIFE annuity income from age 65 (or from age 70, or from anywhere in between), then you can reduce that income stream roughly 45% by making a property pledge. A property pledge doesn't mean the government takes your property. It's merely a pledge to yourself. And it's one property, singular. If/when you sell the property, you can shift the pledge to another one if you wish.
Sure, that's possible. But unless that new medical technology has an "Illegal to use for the benefit of yyhwin" label affixed, you live longer, too, in actuarial/statistical terms. It's longevity insurance, and it will never be lavish, especially (but not only) at BRS level.
OK, and that's why 98.84% (or whatever) of your wealth at age 65 will not be CPF LIFE. Right? So what if that figure is 98.84% or 98.96%? Who cares? Is that what you're losing sleep over right now, seriously?
I don't get what's in your head right now.