I thought that really good hardware was closer to 0.5W/GH. Even Butterfly Labs has equipment that reaches 0.7W/GH.
I don't know of any system that gets close to .5W/GH. Butterfly Labs isn't trustworthy and is many months behind on shipping. The S3 from Bitman seems to be the current best on power consumption (~.7W/GH). Even then that is just the primary power, you also have to pay for cooling. It doesn't leave room for other maintenance costs and staff. Also I used an impossibly low cost for electricity. More likely it is closer to double what I used, even in Iceland. (If that is really where they are.)
I'm not defending Butterfly Labs, but they did send an email one week ago stating that they are now shipping their outdated equipment that people paid for last year. I'm not sure if that means everything is being shipped at once, or over a six month period. I think if we're talking about how certain businesses can still be in business, we should be talking about BFL too.
According to
https://tradeblock.com/mining/, Black Arrow and Spondoolies-Tech both have equipment that get 0.5W/GH. I have not independently verified this, and their information has been known to contain errors. Spondoolies-Tech's SP31 (October) is supposed to get 0.55W/GH. Black Arrow released a press release stating that they will have 0.3W/GH equipment around the middle of next year. There may also be other B2B mining equipment that is not widely known, or these cloud mining companies have an arrangement to buy equipment at wholesale for agreeing to purchase a minimum quantity over time.
The assumption is also that it is not necessary to pay for cooling, since the mining facility would be in Iceland, where fans can bring in cold air. If not for that, then yes, cooling would consume significant power.
What if they have a lot of capital and mine for themselves, but sell contracts to improve their economies of scale? The fact is that we don't know their business model. I think if the business fails, it won't necessarily be because it is a ponzi, but because they made some risky business decisions.