A pitch for the inevitable Kanto-nostalgia-milking-cashcow re-remake (at earliest in gen 7):

Instead of remaking a remake in this tired copy&paste manner gamefreak has been employing so far, why not actually give the original adventure a make-over and improve it?

Keeping the region structure intact, but throwing away all the actual finalized designs of places, remaking them from scratch as they would look if they were created for the first time with current graphics.

GS were direct sequels to Gen-I, hence Johto is turned into Kantos post-game area from now on (at the same time forever eradicating the need for more GS-remakes)

The distribution of wild Pokemon is adjusted and some gen-II Pokemon added to Kantos palette, with the Regional dex rearranged from scratch, while also including the 25 cross-gen evos.
>pic related
Kantodex = 1-180 (181-Mew, 182-Mewtwo)
Johto Expansion = 183-275 (276-Celebi)
notice how some gen II Pokemon are integrated into the Kantodex due to them being encountered there (Houndour, Slugma..), while some gen-I Pokemon are pushed back into the Johto Expansion for the same reason (for example Lapras being found in Union Cave rather than via in-game trade from random NPC in Silph Co.)

-Mt.Moon with a spiralling design and an actual mountaintop
-Cinabar island, completely redesigned, having an actual volcano with wild Pokemon inside
-Moltres relocated to Cinabar volcano
-Gym leaders show up in the Plot, whether it's on the S.S.Anne, the Rocket-plots, or:
-Origin Episode, focusing on Mewtwos creation

-Bill actually creates Porygon
-S.S.Anne functions as a Battle facility
-Battle Dojo from HGSS returns
-Cerulean Cave is now the deepest and most diverse dungeon in any Pokemon game

-Mega evolution shenanigans

that's all I could think of so far
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