> The connections are managed by a fault-tolerant co-operation of devices in the VPC network fabric. Each new connection is assigned a port in a robust and transactional way, while also being replicated across an extensible set of multiple devices. In other words: the NAT gateway is internally horizontally scalable and resilient.
http://perspectives.mvdirona.com/2015/12/vpc-nat-gateways-tr...
> The connections are managed by a fault-tolerant co-operation of devices in the VPC network fabric. Each new connection is assigned a port in a robust and transactional way, while also being replicated across an extensible set of multiple devices. In other words: the NAT gateway is internally horizontally scalable and resilient.
Maybe it just wasn't a priority.