I'm guessing it's referring to doubling VRAM by making them double sided, not using 4GB chips which don't exist.
While the standard allows for it whether or not it's technically and/or financially practical for them to be deployed in GDDR7's lifespan would be debatable. GDDR6 in spec allowed for 1GB, 1.5GB, 2GB, 3GB, and 4GB. Only 1GB and 2GB were ever deployed in market.
I think it should be kept in mind with China we aren't talking about just modding these at home with just a soldering iron or something. It's companies with proper equipment and trained professionals. They've already done it at scale with the 4xxx series.