The people who get into trouble are those who issue original products, such as T-shirts and decals, that use manufacturer logos without the approval of the trademark holder and are made for commercial profit using those materials. This infringes on corporate contracts with licensees who paid good money for the privilege. There was a small decal maker on this forum who got a "cease and desist" notice from Kenworth for selling decals with the Kenworth logo for model trucks. He had to destroy his existing inventory and not issue any more without paying for it.
You are right to be concerned, though I think there would be few problems with showing builds that have already been cleared by the kit manufacturers. Otherwise, there would be no magazines like MCM. But Jantrix is correct about consulting with a publisher. (You're not going to pay for the printing yourself, are you? That would be insane.) And I wouldn't go crazy with preparing a book without showing a prospectus to a publisher so they can see where you're going.
And don't listen to anyone's "logical" guess unless it's based on firsthand experience. Copyright and trademark laws are very complicated, as I have learned from more than 3 decades as an ad agency professional.
Next, I can't tell what you mean about "homemade" cars. Can you show some pictures of what you're talking about?
The progress updates may be like watching sausage being made. You don't want to see what goes into it, but it can turn out pretty tasty.
BTW, for those of you who are interested in using brass, there's a new book out by Ken Foran, who is a master of the art. You can see his work at scalemotorcars.com, where his screen name is xken. And if anybody thinks this is easy, he has a thread over there on building an XKE roadster out of brass; he's still working on the engine and the thread is now 43 pages. My point is, that even the most experienced builders go through some phases where things are experimental and look a bit rough.
Killer job. You're one of the few modelers of this kit that I've seen put in an accurate red interior and open the air vents on the nose. I wonder, though, if the white steering wheel rim wouldn't indicate that it should have banjo steering wheel spokes?
The first Pocher kit I ever saw was an assembled black Mercedes Cabriolet at FAO Schwartz in New York, back in the 70s. Regardless of its shortcomings, it was something awesome to behold (but I'd never attempt to build one).
BTW: Arnaldo Pocher must have been a saint if he was into godsmithing.
It sure is missing some important parts to merit that price (no top, valve cover or oil pan, and who knows what else). Pocher builders may know the answer to this: Wasn't the Rivarossi/Pocher ID plate mostly found on factory-built display models?
One thing, though, is that the question was asking if model building will die out...
Let's not forget that includes military, aircraft, model ships, etc., which have pretty enthusiastic hobbyists, although I don't know how their numbers might compare to model car builders.
Those subjects also make up a huge part of the catalogues of companies like Revell, etc., and may have something to do with their overall budgets regarding how many new car kits they issue.