The only way this would happen is if Microsoft wanted to push the release date to compete with the other platforms in 2016, but when you have the option of:
1) Delaying launch and pissing off fans, for what might turn out to be a detrimental choice
or
2) Capitalizing on the situation and ending the year with positive PR and likely, the lions share of sales in the US which pass on positive pr into the next quarter.
Well, which would you do?