I am wondering about this. To me, it seems that there is still space for a modern, pragmatic language that compiles to native code. Coming from C and C++, I have been using Go recently for applications where garbage collection and some performance loss due to a relatively weak compiler is acceptable.
However, I still find the lack of parametric polymorphism tedious and annoying as well as other stuff you'd come to expect from a modern language (algebraic data types, non-nullable types, etc.).
Does anyone who has experience with Swift think that it could be a better language for the niches Go has gained traction? (Besides iOS/Mac development?)
Since Swift is pushed by Apple, it probably won't suffer from the same ecosystem problems.
What do you expect from a future ecosystem?
Nim has seamless integration with C as it compiles to C anyway, so there should be no concerns about that.
It's amazing that really powerful languages are never mainstream. Lisp, Ada, Ocaml, D and Nim will go their way in the future, they are just not as much in the focus of public attention as modern trends like Rust and Swift which are advertised by big organizations like Mozilla and Apple.
Otherwise, it's a fairly decent language. It doesn't have Go's concurrency baked in to the language, but on OS X you can use Grand Central Dispatch (libdispatch) which is a very decent concurrency library and it works very well with Swift, I'm hoping it will be available in the Linux port of Swift as well.
Besides the more sophisticated type system, a major advantage (or disadvantage, depending on how you look at it) of Swift over Go is it's memory management mechanism: it uses Automatic Reference Counting, which makes garbage collection more deterministic and efficient, at the expense of a certain level of overhead in the developer's thought process (e.g. the developer has to be mindful of things such as reference cycles etc).
D won't be fully a player in that space until the GC is fully optional - meaning no library code causes the GC to run unexpectedly.
I'm excited about Swift for desktop/simulation/gaming/embedded development. I'm sure there'll be a Windows port in the near term as well.