I noticed this too. For a while it had been showing "Shipping 3-29" and then it changed to "Out of stock" and now it's just disappeared completely from the Verizon website. I just called the local Verizon store and asked them about it. They explained that right now inventory levels are extremely low and it's an order only device in their system, so stores typically don't have it in stock right now. When they make a DNA sale these days, they get a quote of 7-8 days for delivery, but have seen the phones arriving in 2-3 days. To their knowledge, it wasn't being discontinued but had been pulled from the website due to supply issues.
About a week ago I was in the store looking at the DNA and the employee there at the time told that it was on backorder and had been for a few weeks as Verizon/HTC were working on a fix for the sim card error issue. That seemed reasonable to me as it was showing "Shipping 3-29" on the website at the time, but I've never read or heard anything since to confirm that Verizon/HTC were actually working on a fix and pulling inventory while they were doing so.
Not sure what that all means or how accurate the info from the sales person is, but that's my two cents.