>>1911Retail card save data will be gone, too.
I guess this only works out if you don't play much on your 3DS, like me. The only save data I really cared about was Smash, and since the Wii U version will be out by the time I'm done with ORAS, it doesn't bother me too much.
And ORAS is £7 cheaper in the AU eShop than in the UK one.