Ada is proof that language selection is political or social, not based on technical merit. My opinion is Ada is a viable candidate language for use today, if you care about what it costs to develop or how long it takes. For over 20 years, the ada compiler and run time have been minimizing defects to a greater degree than any other language / run time. (Note: In my world, C++ has banished ada to the trash heap of 'legacy code', along with ton's of fortran. The C++ replacements are rarely equal; in perfection or in supportability)

Eric Raymond is not a fan of Rust. See "Rust severely disappoints me"(http://esr.ibiblio.org/?p=7294). On one level, he's clearly right. Go was designed to be an simple language that is easy to pick up. Rust had a very different design space. On the other hand, when picking a language for your long-term project, I think there are other factors beyond how proficient you can be in your first few days that should come into play.

Personally, I'm not very bullish on Golang moving into the lowest levels of the stack (the space currently dominated by C and C++). It just doesn't seem like an area where the language designers of Golang are interesting in competing. Swift, on the other hand, definitely has aspirations in this area and it is actively being developed by a company that writes a lot of low-level system software.

I think Go, Swift, and Rust each are interesting in their own way and see them jostling to become the next generation of industry standard languages in the next 10 years.