We’re making a big investment in routing starting in 2.2 to make it interoperate more seamlessly with middleware. For 2.2 this will start with us making a few changes to the routing model, and adding some minor features. In 3.0 the plan is to introduce a model where routing and middleware operate together naturally. This post will focus on the 2.2 improvements, we’ll discuss 3.0 a bit further in the future.
Source: ASP.NET Core 2.2.0-preview1: Endpoint Routing | ASP.NET Blog