I really hope that they turn civ 7 into basically a pseudo team game. Make co-operation so critical to development (science, culture) that you can't exist in splendid isolation and win the game. The game should give you this uneasy feeling of right now I NEED to work together with my opponents but ultimately either I or they will betray each other when we get to the final 20% of the game.
Awesome idea I haven't yet heard om these forums. Trade and diplomacy with other civilisations should be necessary maybe not for short term survival but for long term development and being on top. In history isolated civilizations lose because they don't adapt others innovations, don't spread their influence, have crippled trade... As long as isolated, closed e civilisations can stay on top in civ series, diplomacy is always going to be secondary rather than primary concern.
However I don't really like the notion of AIs automatically hating "winners" by the end game, because it ruins any immersion "this is simulation of the world" in favour of "this is the game played to win". IRL rest of the world isn't suicidally, murderously hating USA, China and EU just for being dominant. Endgame challenge should rather come from natural dynamics of the game themselves - dominant empires definitely should naturally rival and compete with each other; also, civ5 ideologies, tragically removed from civ6, are an excellent natural source of late game global conflicts and divisions. But Mexico shouldn't denounce and suicidally hate US just because of it being, uhm, closer to victory conditions? It should hate US if it harms it interests, sentiments or has contrary ideology.