Dart has a very talented team but they have not filled its potential yet if one is judging by popularity and perception.
Perhaps if a native Dart runtime becomes included into web browsers we will see it grow I just have a hard time seeing it without that piece.
There is also a second JIT-free VM called "Fletch" in the works which is meant for locked-down environments like iOS or Sony's PS4.
Are you referring to Limbo?
Now, with the net et al, languages are adopted much much faster. Go did in a 5 years what too Python 10 years to achieve. Even a transpiled novelty language like Coffescript, caught on widely in just a year or so.
And of course for company sponsored languages, the time to adoption is much much lower. Java appeared and conquered the enterprise space in just 2-3 years. C# got wide adoption in 2 years or so from the MS shops.