I don't think Game Freak is done with cross gen evolutions. I also don't feel like Eviolite has any relation to the issue. I think Game Freak just doesn't find it necessary at this point. The reason Game Freak made so many cross gen evolutions for Gens 1, 2, and 3 Pokémon back in Gen 4 was to celebrate the franchise turning 10. They wanted Diamond and Pearl to be the ultimate games that all players from the previous gens could enjoy and this included giving some of those old gen Pokémon new evolutions. I'm calling it now, when gen 10 comes around and we're close to celebrating the 30th anniversary, I'm betting Game Freak will create new cross gen evolutions.

>Gen 5
The first region not based on Japan. They wanted players to catch new Pokémon that weren't related to any previous ones as to make the experience feel different from past gens. It makes sense that there'd be no new cross gen evolutions.

>Gen 6
It makes sense that they'd choose not to create new cross gen evolutions as Mega Evolution was most likely their prioty when creating new forms for old Pokémon. The only exception to this rule is Sylveon who was created to be the poster child for the fairy-type and to also serve as a teaser towards the then unknown typing.

>Gen 7
They definitely wanted all eyes on the regional variants. They more than likely didn't want new cross generation evolutions and to an extent new Mega Evolutions (which people were also asking for) to steal the spotlight from the Alolan forms.

>Gen 8
Same reason as Gen 7. This time however they found a way to counteract that by giving some of the Galarian forms evolutions that their original counterparts couldn't evolve into. They probably didn't want to have the thunder stolen from these new evolutions that in a way serve as "cross gen evolutions". Also keep in mind that we didn't get any new Megas, let alone the ones we had gotten back in Gen 6 all because of Dynamax and the new Gigantamax forms it gave us.

What do you all think?