Gateway card does have eeprom for temporate save storage for card1 games.Doesn't the GW card have some kind of eprom emulation for card1 games (I recall they at one point in time had saves stored on the gateway card instead of the system SD card).
I would imagine they could add a special update where you can put it in "Sky3DS" mode where it basically behaves like a Sky3DS...Only it can be updated and could truly be unblockable. Sky3DS users are stuck in this illusion that their card will remain unblocked forever and trust me it won't. They built their house on the edge of a cliff and won't realize it until it's too late.
As for updating it to behave like sky3ds...maybe its possible, maybe not - we just don't know. And sky3ds could be using updatable FPGA too.