My rule of thumb is, if you need to switch a primary production language more than once a decade[1], then you're picking them wrong.
Personally, I've been using Java for over a decade, and a few years ago I added Clojure to the mix and expect it to serve me for over a decade, as well. I like them both and believe they both qualify as good picks. I'm also adding Kotlin now, too, mostly because its switching cost and added risk are practically zero.
[1]: for reasons other than targeting a new platform
Speaking of which, Estonia recently implemented a "no legacy" directive [1], under which all government systems will be rewritten from scratch at least every thirteen years. They are taking the stance that a good implementation will last around a decade, not less, but also not much more.
Seconding Kotlin coming from Java. It takes maybe 2 days to learn everything in the language if you already know Java, and it fixes pretty much all the warts that bother me about Java (the big ones for me are immutable references, first-class/higher-order functions, and unnullable-by-default references. Type inference and string interpolations are handy as well). It also has a small enough runtime/stdlib (unlike Scala or Clojure, which I've also tried) to make it practical to use in environments where startup time matters, specifically Android.
Absolutely, I need to learn about Kotlik, it almost looks like Scala at the first glance.
I agree with you about languages and targeting 10+ years with it. Stability is worth more than anything to me, out of the box performance also important (this tend to be great for older languages) not to mention the std library quality. For these reasons Java is an excellent choice.
Clojure came to me as a total surprise, since I haven't studied CS and because I was surrounded with Perl/Java engineers for a long time I haven't heard about Lisp till 2011. It changed my approach to software engineering a lot. It is absolutely eye opening, mind blowing and all that jazz.
Personally, I've been using Java for over a decade, and a few years ago I added Clojure to the mix and expect it to serve me for over a decade, as well. I like them both and believe they both qualify as good picks. I'm also adding Kotlin now, too, mostly because its switching cost and added risk are practically zero.
[1]: for reasons other than targeting a new platform