Because one Sherlock Holmes book is still in copyright in the U.S. it is just conceivable that the Conan Doyle "estate" has a proprietary common law trademark claim to the characters in the book, but it would have to be tested in the U.S. courts. As a previous federal trademark claim has already been rejected, a common law claim probably would not succeed. In any event, all this hoo-ha only concerns the United States. In all other countries of the world, the Holmes oevres are in the public domain. As to the trademark/service mark question, I seriously doubt whether anyone would attempt a claim in any court outside the U.S.
So, in answer to your question, publish and be damned! You could always add the words "Not For Sale In The USA" - a meaningless bit of nonsense, but something that might protect you in the event that the Conan Doyle heirs get their wicked way in the U.S. courts.
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