I don't think that the other phones figure into the Nexus release date that much.
I'm not personally subscribing to any theories that place any of the big three phones above the others in a majority of normal people's minds. Nor do I believe Verizon knows yet which of these phones they should bet on, and I do think they only want to bet on the one that's going to sell the most by itself. I believe that the only thing in danger here is the Nexus reputation in terms of readiness.
The iPhone, Razr, and Rezound all had release dates either announcable or pretty much ready when the phones were unveiled. My original prediction was that if Nexus does not have a release date by the time the other phones hit the store, people besides those of us who are eagerly anticipating it will become aware that one of these things is not like the others. They won't have the benefit of the saner minds and information we have here to balance out straight curiosity. Despite not ever having a hard release date, the phone will be questioned by some larger news outlet seeking to cherry-pick an easy + good tech story. I've seen one minor source already "putting two and two together" and claming the phone must not be ready.
I'm still personally of the opinion the phone will come out before this happens, but with all the ads everywhere on the internet, it could get ugly if it doesn't.
Despite (or possibly because of) all the info I am privy to here, color me still baffled.