There is some speculation to what would actually happen if the timeline was altered. Some say that an alternate universe could be created, or that the timeline is completely rewritten. As to what actually happens, good luck finding a quantum theorist to tell you. As for TOS and the new "reboot" of the movie, TOS still exists, and the movie is now a platform that Paramount hopes to create a new series based on these changes, and get more people back to the Star Trek fanbase. From what I understand, citation needed, is that the movie was ment to exist side by side with the original series, not to replace it. So in essence, that timeline still exists, but as far as Spock (Leonard Nemoy) getting back to that timeline, it is a great improbability. In fact, it could very well mean that everything we know about the original timeline is meaningless when it comes to the altered timeline(yes, that could mean no more tribbles).
You should check out "Ex Astris Scientia" for an indepth answer to this question.