Reposting what I said in the teaser trailer thread:
I think they may be setting up a merge of the Kelvinverse and the Primeverse.
Those sure looked a hell of a lot like Red Matter detonations in that region of space where they were going to investigate the galaxy-threatening emergency situation. And it's somehow tied to YoungPrimeSpock in a way and caused his leave of absence. What if the death of OldPrimeSpock in the Kelvinverse somehow caused a psychic connection to form through the Mycelial Network underlying the universe and connecting all points in time and space, including alternate universes, and that summoned YoungPrimeSpock to the source of the Red Matter events, much like V'Ger would later call to him from across the galaxy?
Much like how Abrams said the ripples from the event that formed the Kelvinverse traveled both forwards and backwards through time, it could be used as a justification for the aesthetic and historical changes in DSC and bring the two disparate timelines into alignment, simplifying things and allowing people from both universes to appear without having to create any more elaborate Treknobbable justifications to do so after this initial event.
I think it's basically setting up the Trek version of
Crisis on Infinite Earths. Of course, I'm just talking out of my ass here and may be reading too much into it, but with all the Kelvinverse nods (the Kelvinverse warp effect, Pike saying "hit it!", the Red Matter supernova-like explosions, and the connection that draws in PrimeSpock) that was the first vibe I was getting from the trailer.
https://www.trekbbs.com/threads/season-2-teaser.295098/page-12#post-12549440