It depends how you define "competitive". If you are trying to collect hipster points then Scala is not going to help you but let's be real. Nobody is writing big systems in either Rust or Swift, these are playgrounds for people at the moment.
I am big fan of Swift and Scala... and, to be honest, for Swift there's a long way ahead before a big system can be deployed... tooling and libs are not there, also not considering that the lack of ABI stability makes the source code necessary for any external dependency.