Again:
Technically it's actually a branching of the timeline that *follows on* from the previous timeline and turns back on itself:
The old continuity still happened- then this happened *after* it.
It's like...
>--ENT--->---60s TOS--->---TNG--->---DS9--->--VOY-->---\--->24th century folks except Spock--->--->
*************************************************\
*************************************************/
*/----<-----<----<--Spock & Nero---<-----<----<-----<-----/
/
\
*\---->---Abrams-TOS--->
Which, coincidentally, is also the way modern science and quantum theory believes messing around with time works.
Yeah I think most people get this. But that means that we havent even been watching the same timeline all these years with the shows and films. Right??? UNLESS this blackhole phenomenon changed the rules I guess.
Trek has NEVER used consistent time travel rules. They often contradict one another, even in the same episode.
Abrahms has resorted to the many worlds interpretation of quantum mechanics in his story, which is the interpretation of reality that more and more quantum physicists are coming to agree with. It solves most of the paradoxes and problems that other methods of time travel pose.