To a degree I think the question you need to ask is what do you want to BUILD? Swift for example pretty much ties you to OSX/iOS... sure there's an Ubuntu version -- of sorts -- but it's really got zero cross-platform potential right now, nor does it look to.
Go shows a lot of potential since it will really compile and is cross platform... Rust I can't say I'm fond of, it's like someone went "you know, C is way to verbose and non-cryptic"... but it's still at least semi-practical.
But in most cases the various 'newer' languages aren't jacks of all trades like C/C++ or even Pascal... which is why I'd probably suggest you just focus on strapping up, putting on the big boy pants, and going for C++. It's not my favorite language by a long-shot, but in terms of there being a compiler for EVERY platform and being able to build almost anything with it, there are few true substitutes right now.