I totally agree with you that the intention was for tony to have been killed, and they did it in a fantastic way with the camera point-of-view idea. The problem I think is that it didn't have the impact that the writers thought it would relating to the "definite ending" they had in mind.
I just saw a short film called "Billy Wilder Speaks" in which he talks of some of the humorous things he experienced in his career as a writer and director.
One item that gave me a laugh was when he spoke about working with Raymond Chandler and told how Chandler would write scripts that contained detailed notes for the camera movements. For example, he wrote that in one scene the camera was to travel "through the keyhole in some door". Wilder seemed to get a good laugh from that. I guess it was because although it might be easy for someone to write, "and the camera goes through the keyhole showing what's happening in the next room", it sets up a big problem for the director. Namely, how to do that.
He sald that the writer should just stick to writing the story and leave it to the director to decide on the issues concerning how the camera is to be used.
I seem to remember that Chase both wrote and directed the finale. If so, that would remove any conflicts between writer and director. As a matter of fact, Wilder insisted that after writing some 25 films, he would write and direct all his future films. I guess he got fed up with writers putting ridiculous instructions into their screenplays.