So if the rumors are true and this game is really a Kanto game, this is what I need to see to make a purchase:
-New areas and redesigned areas for the region. The technology has evolved drastically so the map design should too. Don't just copy/paste the same map tile for tile as they've done for every other return trip to Kanto. With advancements in 3D and the jump to console, Kanto should look MUCH more realistic than it did originally. No tiny routes that you can cross in 5 seconds (Looking at you, Rt. 7, 16, and 18), no routes that are flat as a pancake, even in areas that should be mountainous. Make big cities like Saffron and Celadon feel closer to the likes of Castelia and Lumiose. They're based on Tokyo for Arceus' sake! As for new areas, there's one section of RL Kanto that hasn't really been represented in the games, the Tochigi Prefecture, which is located to the North. So maybe add some new areas north of Rt. 25 based on Tochigi.
-More Pokemon than just the original 151. The Kanto Dex easily has the worst variety out of any regional dex ever, with multiple types not even having enough Pokemon to make a full team out of! And even throwing in cross gen evos and Alola forms doesn't completely solve the problem, that's how dire the situation is. The game should have more than just Kanto families. I don't care if they make completely new Pokemon, I don't care if they make new Kantonian forms of existing Pokemon, I don't care if they just throw in stuff from other regions. Just something more than just throwing in cross gen evos like they did for HGSS and ORAS, that's not enough here.
-An actual story. Kanto's never really had much of a story in the games. The story amounts to "go beat the league and stop Team Rocket from doing bad stuff". Now I don't want it to go full on SM where you stop every 5 seconds for a cutscene or dialogue, but having characters that serve as more than just punching bags or NPCs would definitely improve this game. And Team Rocket needs an actual plan beyond just "invade random areas for the lulz", I want to see them put together a master plan that makes them a legitimate threat instead of just being random thugs.
-New features and things to do. Kanto's tended to be a very barebones experience. It doesn't have its own regional gadget or other neat features, it doesn't have a lot of side activities. It's mainly just same old, same old. This is not going to be acceptable in a modern console Pokemon game, the game should have plenty of character in its extra features and have plenty of things to do outside of the main campaign. It should have a robust online mode (and not one as obtuse and inconvenient as Festival Plaza), a side activity of some sorts with as much depth and content as Contests and Secret Bases, battle facilities to enter (and more than just the generic Battle Tower clone please), and plenty of QoL features. Kanto would have a LOT more life and identity if they include these kinds of extras.
If we don't get a game of that caliber, then no sale. There is absolutely no excuse for this game to not feel like a dramatic improvement, not when this game is supposed to be a modern take on Kanto on a modern console.