It's not just about a framework. Some marketing/evangelism is needed. Those factors were major contributors to the rise of Go.

And the Swift community itself needs to work on making it officially available on more platforms. Officially, the only non-Apple platform that is supported is Ubuntu -- not Linux, Ubuntu. It runs on other distributions, but having “official” support for more platforms would be a big step towards acceptability. Most people I've talked to still consider Swift on Linux an experiment. Even C#/.Net Core seem to be more popular on Linux.

Having Windows support would make the language more acceptable by cross platform developers -- leading to more high quality libraries being written.

With a name like 'vapor', I thought this was some sort of joke. But this looks like fun! https://vapor.codes. An example from that page:

  import Vapor
  
  let drop = try Droplet()
  
  drop.get("hello") { req in
      return "Hello, world."
  }
  
  try drop.run()

Hey, I'm using Vapor (in production). It's really great to work with and moving fast - feels like the early days of rails. There's a real technical advantage to having the brevity of swift (like ruby) but with the type checking of the compiler. I actually migrated this app from Node.js and it's faster and easier in almost every way (notably lack of 3rd party libraries).