Um, Neal's not a lawyer, he just deals with them from time to time, mostly because he's a good target for being framed. Yeah, that's it.
I'm of the personal opinion that it really wouldn't be sufficient for GW to simply rereleased their old models, even if that were possible. The newest epic models (FW releases and initial E:A rescupts) are far above the older models in terms of detail. Further, nearly all of the available plastic infantry, with the exception of those character models that were made for E:40k, are very low quality and have inconsistent scale. That means that most of the product range would need a refresh anyway. I assume that was the thinking behind FW's earlier attempts at epic releases - more highly detailed versions of parts that really no one needed.
Now, as for people infringing on IP, etc., I do understand that is an issue, but there is a line between designing GW rip-offs for profit, and making models for your own personal use. Of course, IANAL. In any case, no one is discussing duping minis here. We're talking about parts that are all designed from the ground up from scratch, that noone is making any money off of. I fail to see how that is any different from someone scupting their own 40k minis from greenstuff and casting a few copies (which is something that is done and is generally allowed in GW tourneys).
As it is, GW is already facing competition within it's own IP (more or less) in both 40k and fantasy. There are companies out there that sell alternate scupts for head swaps, body swaps, weapon swaps, etc. for both 40k and fantasy. Those companies get away with it because most GW stuff is pretty generic anyway - orks and humans and elves and dwarves. What people around here do is quite a bit different, though, but no one here is a commercial concern (not yet anyway).
The time is coming, though, when 3D printing will get to the point that people with hobby cash will be able to draw up not just game pieces, but entire plastic injection molds. That technology exists now, but not at a sufficient detail size or price point. In less than ten years that might not be the case. When that happens every college student with a rudimentary knowledge of 3D graphics and a penchant for tabletop wargaming will be making (mostly crude) models, and most likely making the files freely available to their friends. When that happens GW will be out of luck, like the recording industry except with less money to spend on lawyers.
I think a good solution for GW would be to set up a separate design office (like how FW is separate) with the purpose of inviting fan-made models to be submitted, vetted, then released on a small scale. I mean, if we can do it, surely they could too. It would be a 4 man operation, at most. GW could probably even get away with not paying the scuptors beyond a simple, "congratulations, your model was selected!" But I digress again.
Back to the topic at hand, orky turrets and vehicle parts - engines, tracks, wheels, claws, etc. could be something that could be done without much effort.