Yes I do agree that Apple has that marketing power. I am also sure that they will be selling loads of Apple watches. However if we look at the specification of the Microsoft Band, one thing stands out.
1) Microsoft band can be paired with any device, WindowsPhone, Android and iOS. This is a real advantage for the band, as the Apple watch can only be paired with iOS device. If Microsoft releases the band globally, they will also get a major chunk of the market, as we have seen that the band has sold very well in US.
2) Next feature is the price point. Microsoft band sells at $199 compared to $349 for Apple watch. An average user would only need to see the time, have GPS, pedometer and heart rate monitor for most of the stuff.
So even if there is no doubt that Apple will sell the watch in hundreds of thousands, Microsoft band still has a chance to sell a lot with the 2 features that stand out for the average user.