The question is not only whether something is sustainable [Cuban economy is sustainable], but whether this is a good thing for a Jew to do.
There is no problem if someone does not chase money, and lives off his meager earnings, as long as his wife is ok with that.
There is no problem, if someone is supported by an honest private person, if he learns according to the donor’s expectation.
I am not sure what are the classical sources for using non-Jewish, or Jewish, government funds dedicated to support of poor by people who are able to work, while there are sources condemning it (make your Shabbat k’hol, but do ot rely on tzedokah)