Anyone think the Pentax 645D is going to lose more sales

APS-C

Just kinda depends on how you look at things.

Once again, 35mm digital cannot not match medium format 645 for depth of field and field of view and ability to punish the images in post production. What 35mm has on larger formats is price, ease of use and high ISO. I would also put auto focus capability in the hands of 35mm but Hassy's new auto focus has been pretty amazing from what I've been hearing.