Sublime is Morrison's commentary on the Status Quo Is God trope, and "Here Comes Tomorrow" is their (highly accurate) prediction of the immediate future of comics
A general theme in Morrison's run is that of old vs. new. This is exemplified in the conflict between Sublime (the oldest sentient lifeform on Earth) and mutants, set to soon take the role of dominant species. Morrison occasionally personifies trends in the comic book industry they dislike as villains within the narrative. note What if Sublime also plays this role? By the time Morrison left Marvel, retcons and deconstruction were just around the corner. note It's possible that Morrison was aware of these stories before they left, and predicted that the near future of comics would comprise "big new changes" that never really change anything. "Here Comes Tomorrow" makes frequent references to great, unknown calamities that did nothing in the long run except make the world more crapsack, and Sublime himself is essentially the personification of the "illusion of change:" the dominant species on Earth changes, but it's really always him that's in charge. And consider this line of his in a metatextual context: "The supermen fight and die and return in a meaningless shadowplay because we make them do it."
- "Control" of every kind is an overarching theme in "Here Comes Tomorrow", and it stands out because that theme is just so inherently at odds with the theme of change and evolution that permeates everything else in this run. If you think of Executive Meddling as another form of control, this fits perfectly. If there's one image that tells you everything that you everything you need to know about Sublime, it's the image of him holding a pair of tongs over a bubbling vat of DNA like a blacksmith at the forge while his "bio-foundries" churn out new life-forms all around him. He speaks of himself like some great, Godlike creator of life...but he's really anything but, because he tries to mold, control and mass-produce all the life that he makes, never realizing that continuous, unpredictable change is an inherent part of what makes sentient life what it is. When you lose sight of the importance of change to life and simply try to control it for your own purposes (like profit from comic book sales), you cease to become a part of nature and become, in essence, an unfeeling machine. This is why trying to preserve the status quo in storytelling can be so disastrous: having to endure change and evolution is an inherent part of life as a human being, so it becomes impossible to truly "create life" (i.e. create great stories and characters in fiction) when you forget to let your creations change and evolve, as all living things must.
Sublime influenced Emma to seduce Scott to cheat
Virtually everyone who uses Kick (Sublime) within the story has something really bad happen to them: Jumbo and Sophie die, Xorn and Quentin go insane, and Beast-15104 is flat-out demonically-possessed. Everyone, that is, except Emma Frost, who mentions that she experimented with the drug at least once. On the surface, nothing seems to have gone wrong with her... until you realize she nearly brought everything crashing down by cheating with Scott. When you think about it, this is the one conflict in the narrative that Sublime had nothing to do with... unless he did have something to do with it, and even the small amount of Kick Emma took allowed just enough Sublime into her body to negatively-influence her personality. Because, honestly, would Sublime really pass up an opportunity to sow dissent among his greatest enemies?