That's not enough.

For one, businesses and other entities also need Internet access. Cloud companies in particular needs a ton of addresses. That's gonna eat up a fair chunk of the remaining 50%.

Two, humanity is still growing, governments across the world are building new housing. That's gonna eat up another chunk.

Three, routing is hierarchical, and infrastructure organisations and ISPs are assigned blocks of addresses, not individual addresses. We can't just have a pool of free IP addresses and assign any address to any house in the world as needed. So even having 50% of IP addresses free wouldn't really be enough.

So in my mind, an IP addresses to household ratio of 0.5 means residential CGNAT is inevitable, even if we ignore legacy issues like individual universities and other institutions owning gigantic /8 or /16 ranges.