Xenoblade already has a good fanbase, the original sold .89m and since then the series has gotten a representation in Smash Bros. Xenoblade Chronicles X is among one of the most anticipated titles on the Wii U right now.
With Splatoon, it is VERY hard to say. Will this hit the right audience at the right time? Will they advertise it intensely? After all, it is a new IP. New IPs generally sell either really bad or really good. However, I feel like this one will sell VERY good. Now it just depends on how good it will sell.
Overall, I expect Splatoon with around 1.5m and Xenoblade Chronicles X with around 1.5m. I have good faith in both games and I hope both do very well. But if any were to sell more, I would say Xenoblade would sell more but not by much.
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