There's definitely a fantasy fifth season of Enterprise I see in my head, that begins with an opening episode implying the Temporal Cold War is still somehow raging. We're shown that for 24th Century characters, the holodeck recreation of the NX-01's final mission is accurate from their perspective, because history has been changed around them.
Let's say that no Romulan-Earth conflict happened between 2156 and 2160, so the Federation charter we see Archer signing was born from different, less disastrous events. Next scene we begin to discover further discontinuities in that TNG Season 6 setting, differences in the Enterprise D crew around Riker and Troi, culminating in a bearded Picard who - while retaining his Captaincy - still has Borg implants. Or a Data, who we only heard over the com until this point, shown to be very altered in appearance. That sort of thing to imply a sense of "You're not where you thought you were".
From there on it's quickly established there's something essentially missing from the timeline now, essential to the Next Generation era being the way we remember it, which the Romulan War was the catalyst for. But alterations not so different that an episode like "The Pegasus" can remain unaffected by.
Enterprise cast still play a big part in the episode, since it's their show outside of this ENT/TNG crossover. But all of a sudden it becomes a two-parter of #98 "These are the Voyages..." and #99 "To Boldly Go..." with Trip's death as a cliffhanger to Season 4 and obviously a resolve coming during Season 5.
Now then CBS All Access, where do I sign that consultant producer contract for this renewed show?