I thought they should have announced the catalogue feature at E3. Could have made a major splash. Regardless, they'll never do it, and I'd be surprised if they even entertained the idea seriously. I suspect the 2TB capability is just to cover for the puny internal storage/sell expensive branded harddrives.
If, however, they get desperate enough to pull the trigger, I wonder what they could do to mollify early adopters who dropped cash on VC games. Can't really pull an ambassador in this scenario. I also wonder how this would affect the eShop. I don't imagine developers are going to be psyched about competing with hundreds of free, high-quality games. Even less so for non-Nintendo published VC games. Pay $8 for Kid Kameleon or play Mario Sunshine for free?