I saw an interview where Ronald D. Moore talked about that in the alternate timeline of For All Mankind he had a news blurb indicating The Wrath of Khan occurs one year after it actually occurred in our timeline, because in the show's alternate timeline it's the first Star Trek movie. In For All Mankind's timeline, Star Trek: The Motion Picture was never made because Star Trek: Phase II became a reality. Although, if this version of The Wrath of Khan is based on a combo of TOS and Star Trek: Phase II, the movie could be totally different and it's possible that it's Xon or Will Decker that sacrifices themselves, instead of Spock. But what if Phase II had been made? If Phase II had failed or the reaction had been lukewarm, it's doubtful Star Trek makes the jump to film, and the II-III-IV trilogy that cements the Star Trek films probably doesn't happen, and without the success of the movies Trek stays a cult franchise. If Phase II had been successful, I wonder how much story material does the show burn through to the point that maybe The Next Generation era becomes completely different? And it's likely that Roddenberry would have had a much more influential hand in making any movie adaptations and the creative decisions therein and Star Trek II-III-IV are radically different or don't happen at all. Either Xon or Decker become embraced by fans as Spock's replacement, or people hate the characters and they're the "Cousin Oliver" of Star Trek. Ilia probably becomes a version of Counselor Troi in Phase II. With Decker and Ilia probably being fleshed out over the course of a television series, it probably means that both Riker and Troi become much different characters if The Next Generation still happens down the line, since Riker and Troi are based on much of what had been fleshed out for Decker and Ilia.