Tribal wars will never be too close till a world's final days. In this game you're rewarded for superior diplomacy, strategy, teamwork and loyalty. When 2 or 3 super tribes are left to fight it out for the win, the victor is decided eventually and after the 70% is achieved the world closes after another 3 months. And this is a very fair way to win a world. For example, lets say the NME vs Growth war was a head-to-head fight and no-one was able to get ahead for months, but then a group of NME or Growth members betrayed their tribe and joined the enemy and then win the war easily riding the momentum, you can't blame the game, blame the players.
To make worlds more competitive Inno should make them bigger (=more players) like the first ones. That means more good players and more good tribes, which means the real fights last longer till 1 tribe just nobles whoever is left till 70% (like we're doing atm in NME).
This game is revolved mostly around diplomacy, tribe relations, betrayal, spies, deals and secondarily it's about skill and tribe chemistry/teamwork. So when people play to win, they try to make the best move to secure a win, without risking unnecessary wars. This will never change, unless tribal wars changes massively. In every world, one tribe will always win and the end-game phase will always be easy for the winner, because there wont be any fighting left in the rest of the world.
So i cannot see this 'a race to the finish with no guaranteed winner until the last few days' happening... Unless you had a way to achieve it in mind?