Of course, if Alsatian had been allowed or supported, more people would speak it as bilinguals, but would it be enough to save it? Thousands of languages are dying, especially those that are spoken in a small geographic area where another language seems economically more useful.
As an example, Romanche is an official language of Switzerland, yet it is disappearing at an alarming rate. Even the Basque language, which is rare in France because of a century of concealment, is not flourishing in Spain. Basque is a official regional language in Spain, and the population that can speak it grows slowly, but now the majority of those who live in the Basque region don't understand its traditional langage. When only 20-30% of the population can speak correctly a language, how long can it survive?
When it has the same legal rights as the dominant language, government funds to help run media and entertainment, and a strong culture determined to nurture it, I would argue that it can survive indefinitely. All of which are the case for Basque, which is in fairly rude health at the moment.
Which is kind of at odds with the idea above that "It's more comfortable to blame an abstract entity like the government than your ancestors. "