I think launching it on the same day as OR/AS is kind of a bad idea. I know this could be like last year where they launched 3D World and LBW on the same day. But Pokemon is a sales juggernaut, more so than Mario and Zelda. Launching it on the same day as one of the games that's supposed to improve Wii U sales just seems a bit risky to me.
I don't think their aiming for day 1 or weekend sales. Nov 21 is 1 week before Black Friday in the U.S, the biggest shopping day of the year. So you get a small bang (because Smash Bros is a big series), then you get Black Friday (say $10 off?), bigger boost. then staggered sales for late christmas shoppers. Plus remakes usually sell less, even the 3rd editions, taking that into account I think it would do fine. Is it risky? Yeah. But unless they release it like a month early with the 3DS version (which will probably rush it), theres not a lot of choice.