I remember the Gibson case well (followed it out of both personal and professional interest). I wasn't surprised PRS won on Appeal. The first instance decision was nonsense - nobody spends that much on a guitar without having a fair idea what they are getting into, and the idea that anyone in any way would assume the PRS was a Gibson is bunk. Pretty transparently Gibson were trying to shut down a competitor who made them feel threatened, imo. Otherwise, Vintage would be a better rand to sue (look a lot more like Gibson, and really are a "copy" rather than "inspired by".
That said, what I meant was guitar players were like "ok, fine, it's the PRS version of a Paul, that's cool" - the same people, by and large, who went apeshit when PRS did their version of a Strat. Granted, it was a step further away from *most* of what PRS is known for, style wise (it seems everyone has forgotten their early 90s EG models, which are pretty damn close to these, if less blatantly "our version of the Strat), but still.... why was one shrugged at and the other the apparent crime of the century in the eyes of so many? I don't think for a minute that any of them thought twice about the Gibson v PRS case. Fender, if memory serves, did register their headstocks as TMs in the mid 50s, though they couldn't do that in the UK prior to 94, or much of the rest of the world as shapes weren't registrable as TMs until the TMs At 1994 (in the UK). Prior to that, it would have been the much murkier common law issue of passing off / goodwill in the overall look and such. AFAIK, they can still protect the headstock shape now, but yes they lost everything else about the look of a Strat or Tele long ago. (As an aside, it amuses me that the headstock is the bit they're still able to protect, given that was the one bit of the Strat that they ripped off from somebody else, arguably - see Paul Bigsby's early prototypes.)
Endorsements are an interesting thing. Definitely true that they sell product; Gibson and Fender so rarely advertise outside of the hobbyist press, but they continue to dominate the market largely because they got there first - all yer heroes play F or G, so you want F or G and when the next generation make it b ig playing F or G because their heroes did the new raft of kids in the audience want 'em.... self-perpetuating loop. At least we have some more variety in the market these days, but still. It's what makes me laugh a bit about people who whine and complain about "me too" brands.... generally exactly the same people I've often seen say they *would* buy X, but for "that ugly headstock - why can't they do a nice one, it's just not as good looking as the Fender..."
Another thing that sort of intrigues me is how I've also long been intrigued by Fender's approach to these things: they might dabble with a few oddballs under the Big F for those who won't buy anything else, but they prefer to buy entire brands rathe than compete, then let the brand be what it was. Why copy Gretsch when you can own Gretsch? I see they've even revived the Starfire range that they killed off when they bought Guild, though interestingly now it's being sold as "Guild Starfire" with Guild on the headstock - a stratification of the main brand same as has worked for Gretsch. But I'm digressing here....
If some big name played Shijie, they could take off right enough. I remember Hagstrom becoming much higher profile after Pat Smear played one in Nirvana, and we'd probably not have brands like Eastwood around if Kurt Cobain, Jack White et al hadn't popularised a lot of those defunct sixties oddballs like Airplane and Univox. Let's not forget "Mosrite of California" (nothing to do with the original Mosrite company), who owe their entire existence to the Ventures and Johnny Ramone.