We reached out to Verizon’s PR team and they confirmed to us that if you pre-order the device, even at the subsidized $199 or $249 prices, that you will get to keep your unlimited data package (assuming you have one now). If you are a new customer or are adding a line, you would be subject to the $30 per month, 2GB tier.
We aren’t exactly sure what will happen to those of you that do not pre-order and wait until the phone is actually launched, as there is a chance that Verizon will have kicked off their shared data plans by then. If that is the case, you may have to accept one of their new shared data tiers if you choose to buy the phone at a discounted rate at that time.