The "blood sacrifice"
Charlotte Hale, the board's newly introduced executive director, wants Ford to retire. She's worried about the volatility of his reverie updates, as displayed in a violent scene with Clementine in the Mesa Hub. "The gods... they require a blood sacrifice," Charlotte told Theresa during their conspiratorial tête-à-tête. "We need to demonstrate just how dangerous Ford's creations can be. ... We need someone thoroughly unexpected."
It was an eerie exchange that resurfaced several scenes later, when, approaching the precipice of death, Theresa heard Ford reference the same cryptic phrase: the board tests "me every now and then -- I think they enjoy the sport of it. This time, they sent you. Sadly, in order to restore things, the situation demands a blood sacrifice."
Was Theresa the blood sacrifice all along? The answer can only be yes if Charlotte is in cahoots with Ford. And that's a twist I hope we don't encounter, as it would suck all the fun out of the creative director's antagonistic relationship with the board, and it would ooze cheese like stuffed crust pizza.
A more hopeful reading: Theresa is Ford's sacrifice, but not Charlotte's (hers would be the newly lobotomized Clementine, or worse, potentially a park-goer). Ford likely echoed the phrase to assert his power, showing Theresa that he overheard her conversation with Charlotte (via Hector) and that he's privy to the board's plans of a coup. For Ford, Theresa had to die so he could protect his hold on the park, and so he could flex his muscles at his enemies, the pesky moneymen.