I don't think that's gonna happen. The reason Mother ended is because of Itoi himself thinking that Mother 3 was a perfect conclusion and that there isn't any need for a Mother 4. The series itself actually sells relatively well despite its niche status. 3 million for the whole series if I remember right? Not counting the recent (or not so recent now) VC release for Earthbound.
Xenoblade is like that. It's got a cult following and even though it's no million seller, I'd say sales are good for its kind of game. Unless the director of the games decides that there's no need for another Xenoblade, I can see it going strong for a while similar to Fire Emblem with how Monolith Soft sems to be pushing for the series and Nintendo being behind that. Shulk being in Smash is a very good way to promote the games, as well. Also helps the game didn't take nearly two decades to come to Europe.
EDIT: I knew about Xenoblade because I pretty much try to keep up with the industry. The game's amazing reception isn't something I could easily avoid. lol I did find it in stores (europe here, this was before the NA release) but it never caught my attention since it was expensive. I don't think I'll ever play it frankly, since the price keeps going up and I honestly never liked very long JRPGs (and RPGs in general) with only a few exceptions. (SMT3: Nocturne and Earthbound, really.) It's just not my cup of tea, unfortunately. I am keeping up with chugga's playthrough though, for what it's worth.