It's been discussed before, and it's not going to happen.
You'd have to be able to replace surface-mount memory modules, replace (not update!) the firmware in the built-in RAID controller to recognize the larger memory modules, and last but not least you'd run into a limitation with the addressable space that SD memory supports -- that's why Panasonic no longer uses SD memory in their 16GB and larger P2 cards, but SDHC memory.
