Xenoblade is fairly niche-ish, but for a JRPG positively plastered in anime, it's done well for itself commercially in parts of the world where it's a bit harder to crack through.
If you think about it, there are only a very select few JRPG franchises that are actually
big outside Japan, so Xenoblade not being one of them isn't that damning.
But no, it's not one of Nintendo's big franchises, just a fairly active one. Perhaps the attention it gets online gives it a misleading impression, but online is not a proportionately accurate measure of total audience size. It's not a faithful microcosm.
I wish Nintendo tried as hard with series like Eternal Darkness and F-Zero.
IPs that weren't necessarily
unsuccessful, but don't have a dedicated, steady developer (Metroid, F-Zero, Star Fox, DK, Kid Icarus, etc.) have a tougher go than those which seem to have a specific team tied to them. If we're lucky MercurySteam can stick with Metroid, WayForward with AW, and that alleged EPD Tokyo team with DK so to protect those series from going back into flux.
And Star Fox just desperately needs a team which can understand, evolve, and dedicate themselves to that franchise. Nintendo has no clue was to do with it.