It will sell well but I don't belive is going to be a system seller

Sadly, no
Not bomb tier but pretty meh

It will do much better than that.In Japan alone the game is close to 150k sold, and as most nintendo games, it does much better in the west.But in the case of zenoblade, the first one soldthree to four times more in the US alone compared to Japan sales.So yeah, it will easily pass 500k.

Easily over 1 million with or without marketing.

I dont understand why people are underestimating this game so much.It sold on Wii almost 1 million and will probably have a good boost now that is released in the europe eshop, and most likely is also comming to america.And you have to consider that the game had ZERO marketing here.And while the wii install base was of 100 million, most of them were casual players, and xenoblade isnt the type of game for those people.
Now X is having a very good marketing, with the game appearing in directs, and in important shows as E3 and gamescon, not to mention its going to have a bundle here in the west.And games like Xenoblade, which appeal most to hardcore gamers, tend to have a more loyal fanbase.So we can expect at least the same number of sales that xenoblade had in US and europe(In Japan is already going to outsell the original, with the game comming close to 150k including digital).
I really believe this game will do very well, and i wont be surprised if the total sales by the end of december(Shipped+digital) is higher than 1 million.

The last entry didn't even sell 1 million on the WII so what's to say the same from not happening with Xenoblade Chronicles X on the WII U ...

It will sell at least 1 million.

Less than Splatoon for sure.

The original would have sold 2 worldwide if pirated copies were included. I would expect the same here. Smaller install base, but more hype.

I'd hope so.