Making money isn't difficult for Amazon. They earned $1.1 billion on $34b in sales for 2010, without much apparent effort toward profitability. They've demonstrated at various times that they can generate profit at will.
Clearly Bezos believes it's far more valuable here and now to invest into winning market segments like AWS or digital content (eg streaming vs Netflix) or competing in tablets.
With $61b in sales for fiscal 2012, I don't think it would be surprising if they could generate $3 or $4 billion in profit on that basis, with a strict focus on that. They're obviously never going to be a profit machine however, not without Walmart-like scale.
The numbers don't look good for future returns off of the $116 billion market cap. If you assume they have a great decade and reach $150 billion in sales, with 5% margins, that's $7.5 billion in profit - they'd be fairly valued today on a profit projection seven years out. Shareholders can expect exceptionally low returns on average over the coming years.