My hope for Civ 6 is for all victories to require more work to achieve so we can have a more prolonged end game where we get to actually use modern units and buildings even if we're technologically further ahead of the AI that the Victories are of such that the AI has time to catch up in tech and potentially bother our approaching victory path with NUCLEAR WARFARE! In Civ 5 i would blow through the last few ages within a few turns with bulbing/RA's/free techs and a win by culture/diplomatic would be only another 20-30 turns after doing this. It really didn't allow for endgame combat or buildings to come into the fold at all and the AI are always left in the dust technologically with no time to catch up before the end of the game. Victories would need to require something more than just waiting 100 extra turns after finishing a certain milestone towards that path, otherwise the endgame could feel pretty boring just waiting down a turn timer. I imagine for example gunning for a culture victory where it takes quite a deal longer to win while you had the tech/culture and finished the trees first some other AI's had time to catch up and are now doing well in religion and another is conquering everyone and everyone has now teched up/cultured up and can fling nukes at each other to slow the other guys down, that sounds pretty fun.