Chafetzchaim, I am in accord with DaMoshe.
My father O”H was a great Talmid Chochum who did not have smicha. He was every bit as learned as any Rov I have ever met, but he never went for smicha and would not have called himself Rabbi, though unquestionably he would have passed any bechina given to him. His learning WAS strictly l’Shma, and he had an eidetic memory, so whatever he learned was committed to his memory immediately. He was known for his shiurim and lectures that were typically spontaneous in nature, without notes, and he could quote seforim by heart. He SHOULD have been called rabbi, but preferred not to receive that title.
So I repeat, someone who has honestly earned that title (I love the word honorific), deserves to be called by it, if he so chooses, just as a non-practicing doctor, retired govt’ official (i.e. Mayor Koch O”H),or retired military man is still called by their title. It makes no difference if he has a shteller or teaches in Yeshivah. He still has the degree. Now, OTOH, I kind of believe that a wife of a rabbi should be referred to as the rebbetzin, if in fact her husband is a practicing rabbi in a shul. I am sure there are those who will disagree with that, but it’s a semantic issue, I guess.