I've seen many programming languages become popular (or fail to) over the years and this quote has always seemed to hold true.
With Scala there was the first wave of people working in it that claimed that it was a grand panacea for all the problems in software (as is always the case with new languages).
However, it wasn't until people started to really claim that the language was certainly doomed that it clearly was a success.
In general I have found that Stroustrups quote is, counter-intuitively, a good way to determine whether the next hot new language will really stick or not. Furthermore, I have to admit that even some of my favorite programming languages fail this test and honestly these languages are extremely unlikely to ever achieve mainstream success.
And if you really think about it, it's not so counter-intuitive. Programming languages don't show their real limitations until you are very deep in a large complicated project. The frustrations of the beginner are never the same as the frustrations of an expert and only an expert can really feel that a language is "doomed". This sense of "doom" is often just the realization of the once language X zealot who now sees that this new language is not a true panacea. But this moment of disillusionment is also the moment an idealized programming language has proven itself a practical one. The more people that feel this loss of faith in their favorite new language, the more people are building large, practical, real-world software projects with it.