Next part:
+ Ash with Lucario and Goh with Cinderace VS Eternatus: It doesn't surprise me, honestly. Everything aimed that Ash's Riolu and Goh's Cinderace will evolve soon enough. What it surprises, however, is seeing them against Gigamax Eternatus. I know Eternatus already appeared in the anime, but this battle it's the climax of Galar's region; so I believe this is too soon for that. Ash should be at some steps of the Master Class for this battle to happen. By the way, I think I saw an announcement of a playset figure of Pokemon representing this scene; only the Pokemon shown were Pikachu, Scorbunny, Lucario and Greninja.
+ Slumbering Weald: This scene called my attention too. Although it's too son for Ash and Goh fighting Eternatus like in the games, maybe they will fild the Rusted Sword and the Rusted Shield that they will eventually need for that battle and summon Zacian and Zamazenta.
+ Ludicolo and several Marshtomps: First thing to come to mind is the potential return of Brock, but I'm not entirely sure. Other than that, maybe these Pokemon will be the main characters in a future episode and will become an important role. If I have to guess, maybe Goh could capture the Ludicolo (who might be the evolved Lombre from the other episode); and although I'm not entirely convined, MAYBE Ash could get one of those Marshtomps. Swampert could be a good Pokemon for Ash, when I think of it.
+ Goh capturing Zapdos and possibly the other Kanto's Legendary Birds: I believe this is officially ridiculous. I mean, There's no way you can capture Zapdos, Articuno o Moltres by just throwing a Poke Ball like Goh mostly does. If Goh does this, it will be a big insult to fans' intelligence. This is not like Ash capturing Meltan and then it evolves into Melmetal. Then again, I think this could actually involve their Galar's Forms at some point.
Or Goh catches all three Kanto Birds but Ash catches their Galarian counterparts.
Funny, the same idea came to my mind. It would be silimar to how Goh captured the Kanto's Farfetch'd while Ash captured the Galar's Farfetch'd.
Last thing to say is that, very likely, this opening will suffer several updates as time and episodes pass. Some examples:
+ Pokemon evolving: Raboot evolving to Cindearce, and Riolu evolving to Lucario. Several scenes will have to be adapted when this happens.
+ Ash's Farfetch'd and Riolu: Surely this will become Sirfetch'd vs Lucario at some point.
+ Team scenes: Surely they will be adapted with new captures and evolutions. Ash's scene could change with Riolu and Farfetch'd evolutions, and any other capture Ash can have in the future. In Goh's team, Raboot's evolution will be adapted, but maybe Skowet and Sobble will evolve too. I suspect Goh's giant Magikarp could soon evolve to Gyarados too.
+ Random scenes: The scenes with Alola's gang, Celebii, Ludicolo and the Marshtomps, and Galar's Fighting Gym Leader could be replaced once their episodes are passed.
+ Final scene: This scene could suffer modifications too, showing Ash and Goh's teams, according to new captures and evolutions.