I don't really think that the 3DS XL is an attempt to make all previous 3DS owners cash out extra money, but to give consumers more options when buying the portable. I think it has the same kind of intent that the DSi XL had which was "What one do you want? A large one with big screens, or a smaller one that is easier to take on the go". Sure if that causes people to jump ship from their current 3DS' Nintendo would be all about that, but I wouldn't say that Nintendo wants 500+ from people who already own a 3DS.
TL:DR 3DS XL is about options not money milking consumers.
Anyways, just stating my opinion, but back to the question. What am I getting? Probably both. What am I buying? The 3DS XL when a color I want comes out (I think they'll put out another color before the holidays. If not/if it isn't a color that I want then I won't be getting one this year) I don't intend on purchasing a Wii U, but I'll probably end up being given one.