When you are doing anything in IT, that is "mission critical", a redundant system is necessary, but I have seen things done by the seat of the pants, with no back up, or redundancy, and I have seen it work out, and I have seen it go bad....
The key words here are "mission critical". I don't think an OTA is "mission critical". There's not a single person out there who's phone is DOA and is waiting on this update. It your phone dies, and it's a "mission critical" tool for your business, you go to Verizon and they replace your phone.
The "mission critical" aspect arises if the update bricks your phone. This update, while allegedly really cool and all that stuff, doesn't meet the standard of "mission critical" as I understand it. Paying all the additional costs of redundancy for a "nice to have" update isn't cost effective.
Besides, we're only speculating that the delay is a deployment systems issue. I suspect, (just my opinion) that the delay is likely due to a bug that potentially could have destabilized more phones than they cared to deal with. Be patient. They'll send it when it's ready. Besides, it seems to me that the longer this delay stretches out, the more features the update contains. Maybe if we wait long enough, the feature list will grow to include ending world hunger and global peace!