In what capacity and when is unknown
So that's why Shulk is in Super Smash Bros.
After showing off the "New 3DS" model during their Japanese Direct, Nintendo cut right into some footage of Xenoblade Chronicles on the 3DS. Very little is actually known at this point, but it is confirmed that it will be a port of some sort, and it's coming to Japan next year -- I'm sure a localization is in order eventually.
Here's the bad news. Based on what Iwata stated in the Direct, this port, and a few other future games will only be playable on the New 3DS due to its upgraded power. Fragmentation!