The FSF is a tax exempt charity. There are special rules governing the disposition of the assets of charity in the event of its closure. If the FSF were to go bankrupt it would transfer the copyrights it holds to another organization which is similar in purpose.
The general concern expressed here is not applicable in most places. The concern is basically that the license is _effectively_ revocable (e.g. that new copies can't be made). This isn't expected or believed to be the case in most places, and if it is it's a problem independent of bankruptcy because software authors sometimes turn evil or crazy.
(The situation is not so tidy for patents, on the other hand, which is one of several severe flaws in some of the 'open patent license' stuff— it's believed that otherwise irrevocable patent licenses can be revoked in bankruptcy, a reason avoid trusting freely licensed patents held by anything but charities)