It will sell triple that number in Japan alone FW, as the game is currently outpacing Xenoblade Chronicles X (which sold 85k FW) on COMG and doing on par with Pikmin 3 (which sold about 100k FW).
I get that you're a bit pessimistic about its sales, but declaring that it'll sell Wonderful 101 numbers FW is just as outlandish as claiming it'll sell 1m in a month. I wouldn't be surprised if Splatoon comes close to outselling Wonderful 101's current LT in its first week.
Never claimed it would sell w101 numbers first week. In fact, the post you just quoted I clearly said it would sell more first week. I am talking lifetime sales when I say that, and I am saying it will be close to, not match.
I layed it all out in another thread. I expect w101 to have lifetime sales of 400-500k digital plus physical. I expect splatoons lifetime sales to be 600-700k. I expect it to do about 200k better than w101 lifetime. So it will outsell w101, but not by a ton.