I'm to the post game of Pokemon Sword now, and while there has been plenty to do (and still plenty more to do) throughout the game, I couldn't help but think the other day "this is good, but it's no Pokemon Silver. That post game was basically the entirety of the first generation!"
And that got me thinking, gamefreak missed a great opportunity with their first main line console iteration of the series by not making it epic. They could've gone all BOTW on it, and it would have been awesome.
I'd call it "Pokemon World Tour" and basically it's 64 gyms over 8 regions, starting in Kanto and working your way to the new one for the game (Galar we could say). And each region would be sort of locked, so you could only catch and use the Pokemon introduced in that generation (and maybe being able to go back after beating the region and using the other regions.) I think in Sword I had over 100 Pokemon in my pokedex within the first 10 hours, and could have probably played through the main story in less time than that if I wasn't site seeing, so getting each region concise enough that an 8-region game didn't take like 500 hours seems very reasonable. It'd also allow you to appreciate all the Pokemon without leaving any out, as you'd be able to ease into them.
It could also have been split up into chapters, which would space it out even more for players to explore each area in the current generation. And it could add a neat twist on the competitive scene, with matches being limited to a specific region or groups of regions. I also feel it would have both appeased long time gamers who have played every iteration as it would be full of nostalgia and easter eggs, and new (or returning) gamers who would then be able to explore all the other areas and ease into the massive library of Pokemon.
I do have very fond memories of Silver though. So part of this may be more nostalgia talking and less logic.