MAX-V scalability

Hi,

I am going to use MAX-V type 5M570ZF256 on my new board and I would like to upgrade in future to 5M1270ZF256.
But I found that each of these two versions has a single GND pin which is not compatible to each other: The 5M1270ZF256 uses G5 which is NC in 5M570ZF256, and 5M570ZF256 uses B7 which is defined as IO in 5M1270ZF256.
What should I do to preserve smooth scalability?

Thanks,