Good points, but the Panzer IV is a pretty vital tank, and likely to be popular.
I'm expecting Rubicon to do at least 2 separate kits - maybe Ausf D/E/F and and Ausf G/H/J (possibly with an optional Wirbelwind turret, given that these later versions weren't hugely different from each other so less parts are needed). That would be more manageable, and hopefully give them enough space on the sprues for some extras.