Google switched Google Translate over just last year, November 2016. Considering Facebook is developing all this internally and the scale they operate at and the presumable hardware disadvantages (does FB have any equivalent of Google's TPUs?), switching over in production so quickly is impressive.
Only for very few language pairs, though. But for those translation massively improved, especially for German the old solution was basically unusable.
Google only supports Neural Machine Translation for a subset of languages. Whereas as Facebook is doing it for 2,000 translation directions.
45 languages * 44 other langues ~= 2000 translation directions. There are ~4,500 languages with more than 1,000 speakers ~4,500 * 4,499 ~= 20,254,500 language pairs so that's a very long way from every language.
Frankly though, I imagine the vast majority of those languages are unappealing targets in terms of return on investment.
and much smaller training data..
I guess they really don't need to cover all of them though as most of the people speaking a language with low number of speakers would be able to converse in other mainstream languages as well. I can speak four languages but I rarely converse in two of them as speakers of the two languages are usually comfortable with a mainstream language as well.
Even Swedish is barely in the top 100 with 8.7 million speakers.
The most obvious thing to me is to use an intermediate language - I assume this has already been discussed extensively, anyone have references?