I'm not a Man that's especially into Pokemon (or a PokeMan, for short) but I think this whole debacle about the Pokedex just kinda reveals who badly Pokemon as a whole was thought out. Like, the moment that they started adding pokemon with each generation, they should have though "You know, this is going to get unsustainable if we keep doing this, we should plan ahead how to handle this" and apparently there was 'future proofed' high poly models in X&Y, but apparently that didn't pan out to shit, so here we are with fans getting their toys taken away.
It honestly wouldn't be such a big deal if this was at all expected or justified in some way that the fans could accept, but naw it's just things getting taken away; it kinda highlights the danger of the "Loss Aversion" idea in psychology, where losses feel much worse than gains. Sure the fans are getting new pokemon, new cool 3D stuff, new SuperSizeMe Pokemon powers, but if that little pet they love is getting taken away, those pale in comparison.
I had some ideas just off the top of my head:
Pokemon Natural VS Industrial; where there's an overarching plot line of pollution and large ecological disasters upsetting the biomes of pokemon, causing mass extinctions. Used as an excuse to cut those pokemon that were excluded AND you get to be topical about a real issue!
Pokemon Yarn & Wool; where there's a Yoshi or Kirby's woolly world aesthetic, and it's basically treated as a pokemon game INSIDE the pokemon universe, and then you can make the excuse "We can only make so many yarn and wool-themed pokemon equivalents, so we're cutting the pokedex to a very small number of Mons, just for this game guys, no need to worry" and the fans would eat it up. Requires new models and stuff, perhaps more work than the alternative, but it'd be cool.
Pokemon Quentin & Tarantino: where the formula of the pacing of Pokemon games is itself investigated and innovated upon, so that instead of your typical journey through the region fighting the gym leaders, you might be jumping from Main Character to Main Character Pulp Fiction-style, getting bits and pieces of the overall story, and each MC only has a small selection of Pokemon to choose from, justifying the cut backs. This wouldn't be considered a 'canon' game by Pokefans, so they woudn't complain at all about not having their entire Nationaldex.
What I'm getting at is: come on Game Freak, you have all the power and all the design space, do something with it! Don't just give your fans a stupid slackjawed stare and go "uhhhhhh I think we need to cut some Mons here." and think that that shit flies when you have all the options in the world. I don't have a NationalDex, I'm not even going to be getting Sw&Sh, and I think that that's infuriating.