In the discussion of the Wikinews fork (may they thrive), I picked up some comments predicting the death of Wiktionary and Wikiquote, referring to the low numbers of regular contributors.
I don't think that means the projects are dying: I'm an infrequent contributor to both of those projects, and every time I go there, they're better. Wikiquote is continually improving in coverage and accuracy, and Wiktionary has recently gotten new features (e.g. a separate citations tab) and is also going forward. People are checking recent changes: last time I edited Wiktionary, I was adding citations to an article where the current list was in reverse chronological order, and I was too lazy to change it, thinking "someone else can fix this". Before I got to the third citation, someone had fixed the sequence.
The fact that progress is slowing isn't a sign of impending death. As long as the wikis don't stagnate to the extent that they start to get taken over by spammers and trolls, I'm not going to hold a wake.
As for Wikiquote being one of our less useful projects, that's possibly true, but only because the other projects are so awesome! The web is awash with crap quotation websites of with the same misattributed quotes being incestuously copied around - Wikiquote is one beacon of sanity in that whole mess.
-- David Richfield e^(ði)+1=0
The appropriate timeframe is decades, even centuries. Modibund projects, provided there is enough interest to control spam and vandalism are cheap in terms of bandwidth and database resources. If there is concern about their association with the Wikimedia brandname, a subsidiary could be created to host them.
Fred