Where Swift excels is that it has the performance of C for the most part, and it will continue to improve. Another strength is ARC over Java style GC. As the slides point out, to get the same performance with GC, you need 4x the memory. With only 2x the memory, you get 70% lower performance with Java. Most important, though, is determinism. GC is simply not suitable for real time, hard or soft.
I'm very excited about Swift, and the current version of Xcode is working pretty well for me. I love the aggressive goal of replacing the C family of languages down the road...
I'd take that claim with a pretty big grain of salt. The paper they referenced used an experimental GC without use in production. Who knows how well or bad the default collector in the JVM would perform.
Also, it is not exactly recent. Hardware changes could have shifted the result in any direction.
Regardless, determinism is the really big win. :-)
That said, if you're looking for a language that has kept backwards compatibility, that's Clojure. Rich Hickey has a recent keynote that I found very interesting: https://www.youtube.com/watch?v=oyLBGkS5ICk
I don't know how to feel about it. On one hand this means Clojure will probably never fix some obvious mistakes in its standard library, without changing its name (like what they did with ClojureScript). On the other hand, as I said, it is liberating to have code written in Clojure 1.0 still working in 1.8.
And in spite of all problems with Java and its standard library, there's something very liberating about having code written in 1997 that still compiles and works in 2017.
And the beauty of Java is that it became a platform, so if you hate the language, you can pick another that's closer to what you think programming should be, like Scala, Clojure, JRuby, Groovy, Kotlin, etc. and still benefit from that piece of code written in 1997, all made possible due to Sun's fanatical devotion to backwards compatibility.