Now keep in mind this is when Xbox One first goes on the report. The Xbox One comes out In japan sept 4 or 6 depending on what confusing source you decide to believe, but most say 6th so eh. This would be on a Saturday meaning that report on Xbox One sales will not happen until 6 days later..
The first thing people should think about is that Xbox has had decent opening before. The Xbox 360 did over 250,000 however, it was also cheap and released with a decent library,
The second thing to think about is that the PS4 while games being an issue, opened at around 300,000 although the lack of real game announcements hurt it quite a bit and still have this issue.
SO NOW we get to the Xbox One launch. The Xbox One will be launching with 29 games and 3 confirmed SKUs and one rumored one: Xbox One with Kinect bundled with Kinect Sports and Titanfall, The Kinectless SKU, a regular Kinect SKU, and a rumore Kinectless SKU bundled with Crimson Dragon and Killer Instinct.
Out of the 29 known (it is said they added a few more but they have not brought those out to the open yet) you have 2 exclusive Japanese games and 8 Multiplatform japanese games (3 with additional content, making a total of 10 Japanese oriented games at launch. This along with 7 European games, 3 General Asian games, and 9 American games.
This opening is the complete opposite of what we saw from the competition. While it is still debatable how the legs of the Xbox One will be and also, it will launch before TGS, it could go either way in staying consistent. But I believe that the Xbox one due to this will at least have similar numbers to the PS4 launch or at max a bit more.
The Japanese price of Kinect Xbox One is equal to roughly $450 while the Kinectless is roughly around $350, but keep in mind the rise of taxes and inflation of japanese yen so these are actually some good deals similar to the U.S. pricing.
I think that the 300,000 range is what the Xbox one will due, it may be possible to slightly pass the PS4. I am a little iffy of it doing 400,000 opening.
But keep in mind this is just the opening.