牛津词典对名词disruption的释义有二：

1 a situation in which it is difficult for something to continue in the normal way;

2 the act of stopping something from continuing in the normal way

在本句中disruption为第二义，即其它快递公司可能采取的足以影响联邦快递和联合包裹服务这二个公司正常业务的行动。本句中根据上下文可以翻译为“挑战”。

Analysts say infrastructure such as this makes FedEx and its rival, UPS extremely difficult to dislodge from their thrones atop the U.S. shipping industry. And yet as dominant as they are, the stalwarts are also vulnerable facing a fresh wave of potential disruption.

译文如下：

分析家门说，这样的基础设施使得联邦快递和联合包裹服务这两家快递公司在美国航运业的宝座难以撼动。但是，尽管它们占有主导地位，在面对其它公司新一波的潜在挑战时，它们也是有弱点的。