It can be all too easy for people to underestimate the halachic significance of minhagim (traditions/customs). While there are, as I understand it, a variety of halachic issues/differences of opinions, when all is said and done minhagim can and do become halachiclly binding in certain circumstances.
There are certain minhagim, however, which are mentioned in the Gemara as [at least practically speaking] universal, but today are not observed by significant communities of observant Jews and have not been for generations.
It would seem to me that while it may not be permitted to discontinue a certain minhag there comes a point that "bediavad" (after the fact) is can no longer be considered "customary" to observe a certain practice.
Are there any sources which explicitly discuss the status of discontinued minhagim and whether there comes a point when they loose their status as halachicly binding and if there is any mitzvah to re-establish a kosher minhag which lost its status as halachicly binding, whether as an individual or a community?