Eh. "Leonard Nimoy doesn't own Spock," is a fact.
Well, certainly, but it's not really about who "owns" the character. It's about who defined the character and who has resonated with the audience for 50 years. Yes, the original cast are, by that definition, internationally known and iconic.
Okay, so who "owns" the Doctor? Who "owns" James Bond? Who "owns" Batman? Dracula? Superman?
Many of these characters were iconic when they first appeared, but many other actors have portrayed the same character throughout the years (Dracula is the oldest). However, people will have their personal favorites. It doesn't mean they can't appreciate the other renditions, though. But it's definitely NOT the actor that makes the show. If you are saying that it IS the actor that makes the show, that means that the show is rubbish, because the story can't stand without the original actors. But I've noticed that people want the original stories, NOT the original actors, and that they are miffed that the characters were put in an alternate universe.