"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Verizon Sells Out of iPhone Pre-Orders
Both Apple and Verizon's online store show that they have run out of the initial stock of iPhone 4s for existing Verizon customers. The Verizon iPhone went on pre-order a little over 17 hours ago. We don't know what the initial stocks were, so it's hard to determine if it was a reflection of very high demand or poor initial supply.
Verizon does reveal that February 9th at 3am will be the time that non-Verizon customers can finally order the Verizon iPhone. Meanwhile, the iPhone will be available in retail stores starting on February 10th to all comers.