The 1050 was also retired before a replacement was ready, although after something like three and a half years on the market it was pretty much due to be allowed to retire. For the 1070, the feature set holds up a bit better, which brings us back to the question at hand. I'll hazard a guess...

Since they don't have their own factory, they place orders with the factory that builds them (Eastech, in the case of the 1070) for big production runs. We don't know how big those batches have to be, but I'm sure they're not insignificant. With the market thirst for HDMI growing day by day and companies like Onkyo, Pioneer, and Denon starting to get HDMI v1.3 product onto shelves, they may feel that another batch of 1070's would keep the warehouse filled past the point where they have an HDMI receiver ready, leaving them with inventory that becomes hard to sell. The attention being paid to HDMI inputs and the slowly growing number of HDMI v1.3 receivers on the market also means that the 1070 may see a sudden feature set deficit this fall relative to its approaching competition, which is something that the 1050 didn't really experience (it lacked component video switching, but in 2002 or early 2003 that wasn't a huge deal when competing against other $500 receivers).