They know how vicious people will get if they miss their shipping deadline, and seeing as they're massively pushing the boundaries of ASICs they're very sensibly putting in place a way to compensate customer's good faith.

What it means behind the scenes is they already have kit capable of pushing the equivalent hashrate as they've just sold in new equipment, which is frightening! (~7.5PH/s?)  When the new more efficient equipment launches they can keep the old equipment profitable by running it on ultra-efficient (cheap) energy and renting it out.

A very clever company indeed.