I'm a grandfathered Centennial Wireless customer (unlimited USB Modem data plan). They forced migrated us from generic GSM/EDGE modems to Verizon branded Novatel USB760 3G modems in July 2011.
Try getting a used Novatel USB760 (verizon branded) off of ebay, they are virtually free. Switch your plan to it via customer service.
I know that Verizon announced that they plan to kill all Alltel handsets on the Verizon network by early 2013, but I've been hearing from affected Alltel customers that switching to Verizon branded handsets are avoiding termination. Verizon apparently doesn't want to keep the Alltel specific programming alive on their network.