Man, that whole fight reminded me of my TFA rewrite idea I had shortly after it came out. If you’ll indulge my slight off-topicness:
TFA would mostly play out the same way, but there’s no Starkiller Base. Instead, there’s a huge Super Star Destroyer or Dreadnought (sound familiar?) at the center of the First Order fleet. (It would also have been implied that said fleet is all there is of the First Order.)
The Republic doesn’t consider one fleet of ships in the Unknown Regions to be a threat, Leia starts the Resistance, yadda yadda.
Takodana would play out pretty much as it does in HAL’s Restructured, then Rey is taken aboard Ren’s Star Destroyer for interrogation. Finn tells Leia about the First Order fleet and the Dreadnought. Resistance Intel finds out that the FO fleet is headed to Hosnian Prime.
The final battle is a massive space battle between the First Order fleet, the Republic fleet, and the Resistance arrives to assist…
…just as the Dreadnought fires on Hosnian Prime, destroying the capital and the Senate with it. The rest of the battle is fought to allow the rest of the Republic fleet to escape.
Meanwhile, Finn, Han, and Chewie board Ren’s Star Destroyer to rescue Rey. That all plays out mostly as it did in TFA (Han dies, etc.), but during the lightsaber duel, the Resistance cripples the Star Destroyer, and the duel plays out on a collapsing capital ship…much like Finn and Phasma’s fight in TLJ.
The “ground splitting in two, separating Rey and Ren” thing could’ve made more sense this way, and you could’ve had Finn and Phasma’s fight parallel to Rey and Ren’s.
Anyway, sorry for the long derailment, but that was all I could think about when watching that whole part in TLJ.