Don't care really, with FO3 they've started tossing out vaults left and right so a vault getting cut or not explained is not something I have any problem with at all.
But nah, I don't think it'll be in OWB, why have a vault there? Mariposa and Vault-Tech didn't get a vault.
I'm not saying we need Vaults all blatent as you would. I just mean that it'd be nice to know why it was cut (Probably time constraints)
Also, we don't know if OWB is a secret base in the middle of the Mojave, or a top secret facility hidden beneath a huge city, so if it is under a city, maybe a Vault would be nearby.