The article also says the story is driven less by "fixing" continuity snarls as in the original and thus can focus more on the characters. So I expect the changes will be major character transitions like in previous crossovers (e.g. the way Crisis on Earth-X gave us two weddings and a funeral, the introduction of Leo Snart, etc.), or setup for future storylines.
The end of Oliver Queen's journey is certainly one major change, and there's the addition of Ryan Choi. They also said it sets Sara's arc for season 5 of Legends into motion. They're also introducing Clark & Lois's son, which could set up their spinoff. We may see something that sets up the Mia/Canaries spinoff as well. Kate meeting a version of Bruce, or connecting with the wider hero community, could help inform her storyline going forward.
It's too bad it's only in the crossovers that they really get to play with Sara and Oliver's shared history. This is their last chance to do that, so I hope they make the most of it.
