$100M is a lot of money to throw away for something that may not appreciably alter the course of this generation. And to make back that $50 per console "10 fold within a year" each person would have to spend thousands. Hard to imagine that being common just given how many people in this thread are talking about picking up this deal to make the Xbox One their 2nd or 3rd console. How many people already paying for PS Plus are going to carry a 2nd subscription service? How many are still going to buy most of their games on something else?
If there was some magic equation that rendered this price reduction risk free they wouldn't have waited so long. Or stopped at $349.
I think your math is off.
Let's say we're just talking about the $50 lost on the console. Xbox Live subscription for one year already makes that back. It may also be a subscription they don't already have. Thus, they just adapted more customers into their ecosystem AND they haven't lost that $50 anymore in that year. They just made it back 1 to 1. This assumes that consumer never buys another game, but let's assume they did buy a few, now we're looking at 3 to 4x back on that $50 they lost on the console sale.
I think you're looking at it wrong. When I say they make 10x back, it's a combination of wha tit costs to own an Xbox One. You really need to have Xbox Live to use most of the console and that costs money, then you are far more likely to buy games for the system in the next year since you already own it. We're talking about that $50 difference per unit sold here. They make that back off the new xbox live sub... and if it is someone who already has a sub, chances are that person is already invested in the xbox live stuff, and thus likely to buy games in the next year.
You can't base your assumptions off a niche community of hardcore gamers that represent a fairly small amount of the addressable consumer base. There is no point to get an xbox one without getting a live sub. Have you ever let your live sub run out on the Xbox One? YOu can still watch netflix... but that's about it. People are still going to buy Halo and other exclusives for the system (sunset overrdrive, etc), and for most of those game sthey will require you to connect to live to function/update.