
Originally Posted by
fumei
Well, there's a pretty simple theory you could come up with here regarding this.
We obviously can't fight ORT head on (when we're shown the future and are forced to fight it, we manage to take down a single massive health bar (unless you're Bazett, I guess) only for it to reveal 9 more with tens and hundreds of millions of HP, and it's only level 1 in this fight, so they're really hammering in that it's too strong for us), but based on this future we're shown we know that ORT's "goal" once it wakes up will be to crawl out of the Lostbelt and get to Antarctica to devour CHALDEAS and destroy the world. To do that, it obviously has to get to the top of Mictlan, and it's currently sleeping at the bottom. So the simplest theory to how a "story endgame" could play out is just that we'll never really fight ORT. All we'll do is set up stations to slow it down. I think this is somewhat corroborated by the meta fact that when we defeat the Alters in the underworld borders, they don't die or fade away. They stay, because they're "bound" to the regions. The only meta reasoning for this to be the case is if these Servants, with their newfound control over the borders they're bound to, become relevant again. So in that sense, it's very possible that the endgame here isn't about "defeating ORT", it's a race to see who reach their goal first: us going from Chichen Itza down to the Ceiba Tree to fell it, or ORT going from the tree up to the top of the world.
The borders are there to just slow it down, and likewise it could very well be that Tlaloc and Izcalli will help do the same, considering they're currently on Tezcatlipoca's side, but after being shown the future they're obviously a bit more hesitant since they want to create a good world, not whatever this shit they were shown is.