I think what he's saying, in regards to, "And so does everyone else", is a lot of 'mainstream' gamers: A lot of North American gamers enjoy Halo. I'm not saying everyone, but I'm saying there's a lot. If I read this correctly, I think that's what he means.
My two cents on it, are that yes; Halo is extremely popular in North America, and certainly other countries for that matter (played someone from Britian the other night). Japan may not enjoy Halo, but I think (I'd like to think) that there are some fans in Japan who own a 360, looking forward to Halo. However, the biggest area of concern for Microsoft is selling their game to their 'home' market. They wanna make sure their flagship title does well in the states, as that's where they're gonna make money. In the end, I don't think Microsoft will care if Japan/other countries will be interested or not.
Halo will most likely out sell Brawl, on the basis that Halo is getting a 3 and a half(ish) month start. By the time Brawl comes out, I'd predict there will have been at least 1 mil. plus sold. Not to mention, when Brawl comes out, it's in the middle of the holiday selling season; for Nintendo's sake, I hope they make a LOT of copies for Brawl. Selling out of your product is a double-edged sword. It means your product is good, but selling out with nothing left to stock with in the holiday season is bad for business. It's the same problem Nintendo had with the Wii during the holidays (working last year as a manager at Gamestop was an effing nightmare). There was more demand then there was supply. I just hope Nintendo is prepared this time around. Judging from how Microsoft handled last years holidays, they kept 360's in stock, and kept shipping more every couple of days. The only way Nintendo will out sell Halo is if there is enough demand for the product, and if Nintendo has enough supply for the product. Microsoft will certainly have both of those bases covered.