Something always bugged me about the Vex. Their end goal is to live as long as possible,whatever that takes. The Sol Divisive believed the best way to achieve that was to worship the Witness, given they couldn't calculate it at all. So what about us? We kill millions of Vex, some of their strongest minds, and even killed the Witness. Wouldnt those same calculations apply? I.E. "The best way ti survive is to serve the guardians." Something like the Sol Submissive, the Vex finally realizing they would loose far less if they worked with us, given we have beat literally everything thrown at as so far, from any enemy we've faced, and the Vex are kinda the weakest faction right now (besides the Sol Divisive, but even they are arguably the weakest Witness force.)